Manuals




manual_1.3


Quick tutorial:

XML examples manual:

Online user forum

Quick tutorial for almaBTE

almaBTE consists of a library and a collection of executables allowing the user to calculate thermal transport properties of heterogeneous structures, using only ab-initio data, and solving the phonon Boltzmann Transport Equation (BTE).

Features of almaBTE 1.3 include

Supports a variety of material types

  • crystals
  • alloys
  • superlattices

Enables steady-state transport simulations in multiscale structures

  • bulk systems (thermal conductivity & capacity)
  • thin films (effective thermal conductivity)
  • multilayered structures (temperature profile, spectrally resolved heat flux, effective thermal conductivity)

Enables transient transport simulations in bulk systems

  • single pulse temperature response
  • mean square displacement of thermal energy

almaBTE includes all the capabilities of ShengBTE for single crystals (but in a fully new implementation with more efficient solution algorithms). almaBTE is fully written in C++ and freely distributed as open source under Apache 2.0 License.

Installing and compiling almaBTE

almaBTE relies on several external libraries (hdf5, boost and openMPI) that must be installed before compiling the main program. Detailed instructions for each supported operating system can be found below.

Installation on Ubuntu Linux

The following instructions have been tried on Ubuntu 16.10, freshly installed from the official AMD64 desktop image. They should be easily trasferable to other Debian-based distributions, and provide useful hints as to the required packages for other Linux systems.

1. Install CMake and the HDF5 and Boost libraries

From a terminal window, run this command:

sudo apt-get install cmake libboost-all-dev libhdf5-dev

You will be asked for your password. The system will then download and install all required dependencies.

2. Create a build directory

Move into the directory containing the almaBTE source code and run the following commands:

mkdir build
cd build
cmake ..

3. Compile almaBTE

From the build directory, run the following command:

make all

Note: you can speed up the process with parallel compilation. For example, if your CPU has 4 cores, you can use

make -j 4 all

4. Run the set of unit tests

almaBTE can run a series of test to check that the main modules work correctly on your system. To do so, run the following command from the build directory:

make test

5. Add the almaBTE executables to your $PATH so they can be run from any directory

Open ~/.bashrc in a text editor and add the following line:

export PATH=$PATH:"<alma_dir>/build/src"

where <alma_dir> must be replaced by the location of the main alma directory, for example /home/my_user/alma. After saving this change, reload the file with source ~/.bashrc or by opening a new shell.

Installation on macOS

almaBTE requires OS X Yosemite (10.10.5) or higher.

To begin the installation, open a Terminal window and perform the following steps.

1. Obtain Xcode command line tools

From the terminal window, type

xcode-select --install

A popup will appear, click Install and follow the graphic prompts.

2. Update the Xcode development environment

Obtain the current version of Xcode from the Mac App Store. You must have/create an Apple iTunes account to do so, but the download (about 4.5 GB, allow up to 2 hours) is free of charge. Xcode is required for correct functioning of Homebrew and proper compilation of almaBTE.

Once the download and installation are complete, open Xcode from the Applications folder. Accept the License Agreement, then close Xcode again.

3. Install the Homebrew package manager

Return to the Terminal window and type

ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"

4. Obtain cmake command line tools

brew install cmake

5. Obtain HDF5 libraries

Note: as of this writing the latest hdf5 package (1.10.2) was found to cause compilation issues on macOS. The problem can be avoided by installing hdf5 version 1.08 as shown below.

brew install hdf5@1.8
sudo cp /usr/local/opt/hdf5@1.8/lib/* /usr/local/lib/.
sudo cp /usr/local/opt/hdf5@1.8/include/* /usr/local/include/.

6. Obtain boost and openMPI libraries

brew install boost-mpi

7. Compile almaBTE

Navigate to the alma main folder and execute the following

mkdir build
cd build
cmake .. -DCMAKE_BUILD_TYPE=RELEASE
make all

Note: you can speed up the process with parallel compilation. For example, if your CPU has 4 cores, you can use

make -j 4 all

8. Verify that almaBTE components function properly

Run the series of self-tests by executing

make test

9. Add the almaBTE executables to your $PATH so they can be run from any directory

sudo nano ~/.bash_profile

In the file, add the following line

export PATH="$PATH:<alma_dir>/build/src"

where <alma_dir> must be replaced by the location of the main alma directory, for example /Users/my_user_name/alma. Save the file using ctrl-O followed by enter, and close the editor with ctrl-X.

Finally, end the session by typing

exit

and close the Terminal window.

Main workflow of almaBTE

The workflow for performing thermal computations with almaBTE is graphically illustrated in the figure below (click for large version) and typically consists of the following two steps.

1. Obtain phonon properties of the materials of interest

In this step you will use VCAbuilder and/or superlattice_builder. These executables use ab-initio source files (downloadable from our online materials database) to determine the phonon dispersions, group velocities, and scattering matrix for three-phonon processes. The phonon properties are computed over a discrete wavevector grid with user-supplied resolution and stored in <material>.h5 files (hdf5 format). For superlattices, the file also contains the phonon scattering rates induced by mass disorder and barriers.

The hdf5 files only need to be created one single time for each material with a given grid resolution.

2. Solve the BTE for the structure of interest to extract thermal transport properties

For this step a variety of executables are available, each dedicated to perform specific simulations on bulk systems, thin films, and multilayer structures.

Thanks to the previously created hdf5 repository, phonon properties of the constituting compounds do not have to be recomputed but can simply be loaded from the files.

The structure geometry and computational settings are controlled by the user via xml input files.

Using almaBTE: Overview of each executable

Below follows a brief description of the executables.

Executables marked with [mpi] are parallellised; speed up execution by running them on multiple cores.

For a detailed illustration of the xml input syntax and generated outputs, please refer to the xml examples manual .

VCAbuilder [mpi]

VCAbuilder <inputfile.xml>

This executable builds hdf5 phonon property files for bulk materials.

Input

[Required] xml input file describing the desired material and grid resolution.

Several types of materials are supported:

  • <singlecrystal> (e.g. Si, GaAs, InAs, GaN, …)
  • <alloy> (e.g. Si0.5Ge0.5, In0.53Ga0.47As, …)
  • <parametricalloy> Automatic batch creation of alloy families (e.g. Si1-xGex, InxGa1-xAs)

[Required] ab-initio source files downloadable from our online materials database

  • _metadata
  • POSCAR
  • FORCE_CONSTANTS
  • FORCE_CONSTANTS_3RD
  • BORN (polar compounds only)

Alloy creation requires ab-initio files for each constituting compound, for example generation of In0.53Ga0.47As needs files for InAs and GaAs.

Output

h5 file(s) for the specified material(s)

superlattice_builder [mpi]

superlattice_builder <inputfile.xml>

This executable builds hdf5 phonon property files for superlattices.

Input

[Required] xml input file describing the desired superlattice and grid resolution.

The superlattice is described in terms of its two consituting compounds, and the atomic concentration profile of a single period. (For details see the examples.)

[Required] ab-initio source files for the constituting compounds (see VCAbuilder).

Output

h5 file for the specified superlattice.

phononinfo

phononinfo <materialfile.h5> <OPTIONAL:Tambient>

This executable writes phonon information associated with a previously generated h5 file to a tabulated data file.

Input

[Required] Path to a previously generated h5 file for the material of interest.

[Optional] Ambient temperature. Set to 300K when omitted.

Output

Comma-separated data file (including a single-line header) with extension .phononinfo containing the following phonon properties:

  • q-point index nq [-]
  • branch index nbranch [-]
  • first wavevector coordinate qa [normalised to reciprocal lattice vector a]
  • second wavevector coordinate qb [normalised to reciprocal lattice vector b]
  • third wavevector coordinate qc [normalised to reciprocal lattice vector c]
  • angular frequency omega [rad/s]
  • volumetric heat capacity C [J/m^3-K] evaluated at the specified Tambient
  • lifetime tau [s] evaluated at the specified Tambient
  • x-component of group velocity vx [m/s]
  • y-component of group velocity vy [m/s]
  • z-component of group velocity vz [m/s]

kappa_Tsweep

kappa_Tsweep <inputfile.xml>

This executable computes the thermal conductivity tensor and volumetric heat capacity of bulk media as a function of ambient temperature.

Input

[Required] xml input file specifying the material of interest and desired temperature sweep.

[Required] previously generated h5 file for the material of interest

Output

csv file containing the thermal properties

cumulativecurves

cumulativecurves <inputfile.xml> <OPTIONAL:Tambient>

This executable computes the contribution of different phonons to bulk thermal conductivity and heat capacity at a given temperature.

Input

[Required] xml input file specifying the material of interest, thermal transport axis, and desired quantities.

The phonon contributions to thermal conductivity and capacity can be resolved by a variety of properties:

  • mean free path [m]
  • 'projected' mean free path (MFP measured along the thermal transport axis) [m]
  • angular frequency [rad/ps]
  • frequency [THz]
  • energy [meV]
  • relaxation time [s]

[Required] previously generated h5 file for the material of interest

[Optional] Ambient temperature. Set to 300K when omitted.

Output

File(s) in csv format containing the requested cumulative quantities.

kappa_crossplanefilms

kappa_crossplanefilms <inputfile.xml> <OPTIONAL:Tambient>

This executable performs semi-analytic computation of the cross-plane apparent conductivity in thin films as a function of thickness at a given temperature. The program is also capable to provide a compact parametric fitting to the computed conductivity curve.

Input

[Required] xml input file specifying the material of interest, film orientation, and desired thickness sweep

[Required] previously generated h5 file for the material of interest

[Optional] Ambient temperature. Set to 300K when omitted.

Output

File in csv format containing the film conductivity, and optionally another csv file containing the parametric model parameters and curve.

kappa_inplanefilms

kappa_inplanefilms <inputfile.xml> <OPTIONAL:Tambient>

This executable performs semi-analytic computation of in-plane apparent conductivity in thin films as a function of thickness at a given temperature.

Input

[Required] xml input file specifying the material of interest, film orientation, and desired thickness sweep

[Required] previously generated h5 file for the material of interest

[Optional] Ambient temperature. Set to 300K when omitted.

Output

File in csv format containing the film conductivity

steady_montecarlo1d [mpi]

steady_montecarlo1d <inputfile.xml> <OPTIONAL:Tambient>

This executable performs variance-reduced Monte Carlo simulations of one-dimensional transport in thin films and multilayer structures embedded between two isothermal reservoirs.

Input

[Required] xml input file specifying the structure geometry, materials, and simulation settings

The following quantities will be computed by default:

  • temperature profile versus space
  • average heat flux, and its stochastic tolerance
  • system-wide effective thermal conductivity, and its stochastic tolerance
  • system-wide effective thermal resistivity and conductance

Upon user request, the program will also determine heat flux resolved by phonon frequency at user-specified locations.

[Required] previously generated h5 files for all materials present in the structure

[Optional] Ambient temperature. Set to 300K when omitted.

Output

csv file containing the computed temperature profile

txt file containing the thermal metrics

Optionally: csv files of spectrally resolved heat flux profiles

steady_montecarlo1d_powersource [mpi]

steady_montecarlo1d_powersource <inputfile.xml> <OPTIONAL:Tambient>

This executable performs variance-reduced Monte Carlo simulations of one-dimensional transport in thin films and multilayer structures with a planar power source at the top and ideal heat sink at the bottom.

Input

[Required] xml input file specifying the structure geometry, materials, and simulation settings

The following quantities will be computed by default:

  • temperature profile versus space
  • temperature rise at the heat source, and its stochastic tolerance
  • system-wide effective thermal conductivity, and its stochastic tolerance
  • system-wide effective thermal resistivity and conductance

Upon user request, the program will also determine heat flux resolved by phonon frequency at user-specified locations.

[Required] previously generated h5 files for all materials present in the structure

[Optional] Ambient temperature. Set to 300K when omitted.

Output

csv file containing the computed temperature profile

txt file containing the thermal metrics

Optionally: csv files of spectrally resolved heat flux profiles

transient_analytic1d

transient_analytic1d <inputfile.xml> <OPTIONAL:Tambient>

This executable computes semi-analytic solutions of the one-dimensional time-dependent BTE in bulk media at a given temperature.

Input

[Required] xml input file specifying the material of interest, the thermal transport axis, and the desired time sweeps.

Several quantities of interest can be computed:

  • single-pulse temperature profiles versus space at user-specified times
    (only valid in weakly quasiballistic and diffusive regimes1)
  • single-pulse temperature response at the heat source versus time
    (only valid in weakly quasiballistic and diffusive regimes1)
  • mean square displacement (MSD) of thermal energy versus time
    (valid at all times, from fully ballistic to diffusive regimes)

1 Time values must exceed characteristic phonon relaxation times.

[Required] previously generated h5 file for the material of interest

[Optional] Ambient temperature. Set to 300K when omitted.

Output

File(s) in csv format containing the requested transient solution(s)

Examples

This document gives an overview of the XML example files provided for illustrating the various almaBTE executables and their xml syntax.

The .xml files listed below can be found in the /test_resources/examples directory.

Important Note / Disclaimer

The examples discussed in this manual are for illustration purposes only.

In particular, the wavevector grid employed in the examples is purposely coarse in order to speed up the process. For actual calculations we recommend the following minimal settings to ensure sufficiently converged thermal properties:

  • cubic systems (2 atoms per unit cell): <gridDensity A="24" B="24" C="24">
  • wurtzites (4 atoms per unit cell): <gridDensity A="15" B="15" C="15">

Quick Navigation

Example input files for VCAbuilder

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VCAbuilder_example1.xml : Si

<!-- Illustrates creation of a mono-atomic single crystal. -->

<singlecrystal>

  <!-- OPTIONAL. Specifies path to repository containing folders with force constants. -->
  <!-- Equals the current work directory when omitted. -->
  <materials_repository root_directory=".."/>

  <!-- Specify compound name within the repository. -->
  <compound name="Si"/>

  <!-- Specify desired number of divisions for wavevector grid. -->
  <gridDensity A="12" B="12" C="12"/>

  <!-- OPTIONAL. Specifies directory for writing HDF5 file. -->
  <!-- Will be determined automatically when omitted. -->
  <!-- (Name of HDF5 file is always created automatically.) -->
  <!-- Directory is relative to current work directory. -->
  <target directory="../Si"/>

  <!-- OPTIONAL. Forces rerun and rewrite even if HDF5 file already exists. -->
  <overwrite/>

</singlecrystal>

VCAbuilder_example2.xml : GaAs

<!-- Illustrates creation of a bi-atomic single crystal. -->

<singlecrystal>

  <!-- OPTIONAL. Specifies path to repository containing folders with force constants. -->
  <!-- Equals the current work directory when omitted. -->
  <materials_repository root_directory=".."/>

  <!-- Specify compound name within the repository. -->
  <compound name="GaAs"/>

  <!-- Specify desired number of divisions for wavevector grid. -->
  <gridDensity A="12" B="12" C="12"/>

  <!-- OPTIONAL. Specifies directory for writing HDF5 file. -->
  <!-- Will be determined automatically when omitted. -->
  <!-- (Name of HDF5 file is always created automatically.) -->
  <!-- Directory is relative to current work directory. -->
  <target directory="../GaAs"/>

  <!-- OPTIONAL. Forces rerun and rewrite even if HDF5 file already exists. -->
  <overwrite/>

</singlecrystal>

VCAbuilder_example3.xml : Si0.4Ge0.6 alloy

<!-- Illustrates creation of a binary alloy. -->

<alloy>

  <!-- OPTIONAL. Specifies path to repository containing folders with force constants. -->
  <!-- Equals the current work directory when omitted. -->
  <materials_repository root_directory=".."/>

  <!-- Specify compound names and alloying fractions (between 0 and 1). -->
  <compound name="Si" mixfraction="0.4"/>
  <compound name="Ge" mixfraction="0.6"/>

  <!-- Specify desired number of divisions for wavevector grid. -->
  <gridDensity A="12" B="12" C="12"/>

  <!-- OPTIONAL. Specifies directory for writing HDF5 file. -->
  <!-- Will be determined automatically when omitted. -->
  <!-- (Name of HDF5 file is always created automatically.) -->
  <!-- Directory is relative to current work directory. -->
  <target directory="../SiGe"/>

  <!-- OPTIONAL. Forces rerun and rewrite even if HDF5 file already exists. -->
  <overwrite/>

</alloy>

VCAbuilder_example4.xml : In0.53Ga0.47As alloy

<!-- Illustrates creation of a ternary alloy (from 2 compounds). -->

<alloy>

  <!-- OPTIONAL. Specifies path to repository containing folders with force constants. -->
  <!-- Equals the current work directory when omitted. -->
  <materials_repository root_directory=".."/>

  <!-- Specify compound names and alloying fractions (between 0 and 1). -->
  <compound name="InAs" mixfraction="0.53"/>
  <compound name="GaAs" mixfraction="0.47"/>

  <!-- Specify desired number of divisions for wavevector grid. -->
  <gridDensity A="12" B="12" C="12"/>

  <!-- OPTIONAL. Specifies directory for writing HDF5 file. -->
  <!-- Will be determined automatically when omitted. -->
  <!-- (Name of HDF5 file is always created automatically.) -->
  <!-- Directory is relative to current work directory. -->
  <target directory="../InGaAs"/>

  <!-- OPTIONAL. Forces rerun and rewrite even if HDF5 file already exists. -->
  <overwrite/>

</alloy>

VCAbuilder_example5.xml : batch creation of Si1-xGex alloys with x = 0.2, 0.4, 0.6, and 0.8

<!-- Illustrates batch creation of a series of binary alloys. -->

<parametricalloy>

  <!-- Declare mixfraction parameters. -->
  <mixparameter name="x" start="0.2" stop="0.8" step="0.2"/>

  <!-- OPTIONAL. Specifies path to repository containing folders with force constants. -->
  <!-- Equals the current work directory when omitted. -->
  <materials_repository root_directory=".."/>

  <!-- Specify compound names and alloying fractions (between 0 and 1). -->
  <compound name="Si" mixfraction="AUTO"/>
  <compound name="Ge" mixfraction="x"/>

  <!-- Specify desired number of divisions for wavevector grid. -->
  <gridDensity A="4" B="4" C="4"/>

  <!-- OPTIONAL. Specifies directory for writing HDF5 file. -->
  <!-- Will be determined automatically when omitted. -->
  <!-- (Name of HDF5 file is always created automatically.) -->
  <!-- Directory is relative to current work directory. -->
  <target directory="../SiGe"/>

  <!-- OPTIONAL. Forces rerun and rewrite even if HDF5 file already exists. -->
  <overwrite/>

</parametricalloy>

VCAbuilder_example6.xml : batch creation of InxGa0.8-xAl0.2As alloys

<!-- Illustrates batch creation of a series of quaternary alloys -->
<!-- (from 3 compounds) with 1 free parameter. -->

<parametricalloy>

  <!-- Declare mixfraction parameters. -->
  <mixparameter name="x" start="0.2" stop="0.8" step="0.2"/>

  <!-- OPTIONAL. Specifies path to repository containing folders with force constants. -->
  <!-- Equals the current work directory when omitted. -->
  <materials_repository root_directory=".."/>

  <!-- Specify compound names and alloying fractions (between 0 and 1). -->
  <compound name="InAs" mixfraction="x"/>
  <compound name="GaAs" mixfraction="AUTO"/>
  <compound name="AlAs" mixfraction="0.2"/>

  <!-- Specify desired number of divisions for wavevector grid. -->
  <gridDensity A="4" B="4" C="4"/>

  <!-- OPTIONAL. Specifies directory for writing HDF5 file. -->
  <!-- Will be determined automatically when omitted. -->
  <!-- (Name of HDF5 file is always created automatically.) -->
  <!-- Directory is relative to current work directory. -->
  <target directory="../InGaAlAs"/>

  <!-- OPTIONAL. Forces rerun and rewrite even if HDF5 file already exists. -->
  <overwrite/>

</parametricalloy>

VCAbuilder_example7.xml : batch creation of InxGayAl1-x-yAs alloys

<!-- Illustrates batch creation of a series of quaternary alloys -->
<!-- (from 3 compounds) with 2 free parameters. -->

<parametricalloy>

  <!-- Declare mixfraction parameters. -->
  <mixparameter name="x" start="0.2" stop="0.8" step="0.2"/>
  <mixparameter name="y" start="0.2" stop="0.8" step="0.2"/>

  <!-- OPTIONAL. Specifies path to repository containing folders with force constants. -->
  <!-- Equals the current work directory when omitted. -->
  <materials_repository root_directory=".."/>

  <!-- Specify compound names and alloying fractions (between 0 and 1). -->
  <compound name="InAs" mixfraction="x"/>
  <compound name="GaAs" mixfraction="y"/>
  <compound name="AlAs" mixfraction="AUTO"/>

  <!-- Specify desired number of divisions for wavevector grid. -->
  <gridDensity A="4" B="4" C="4"/>

  <!-- OPTIONAL. Specifies directory for writing HDF5 file. -->
  <!-- Will be determined automatically when omitted. -->
  <!-- (Name of HDF5 file is always created automatically.) -->
  <!-- Directory is relative to current work directory. -->
  <target directory="../InGaAlAs"/>

  <!-- OPTIONAL. Forces rerun and rewrite even if HDF5 file already exists. -->
  <overwrite/>

</parametricalloy>

Example input files for superlattice_builder

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superlattice_builder_example1.xml : idealised (digital) InAs/GaAs superlattice

<!-- Example definition of a binary superlattice. -->

<superlattice>

  <!-- OPTIONAL. Specifies path to repository containing folders with force constants. -->
  <!-- Equals the current work directory when omitted. -->
  <materials_repository root_directory=".."/>

  <!-- Specify desired number of divisions for wavevector grid. -->
  <!-- Applies to both components of the superlattice. -->
  <gridDensity A="8" B="8" C="8"/>

  <!-- Main axis of the superlattice. -->
  <!-- na, nb, and nc (integers) specify the direction. -->
  <!-- nqline specifies number of q points in the 1D Brillouin zone -->
  <!-- used to build the Green's Function. Should be odd and at least 501.-->
  <normal na="0" nb="1" nc="1" nqline="501"/>

  <!-- Specify both compound names within the repository. -->
  <compound name="GaAs"/>
  <compound name="InAs"/>

  <!-- OPTIONAL. If specified, do not deal with three-phonon processes. -->
  <!-- <skip3ph/> -->

  <!-- Specify the concentrations of the second compound in each layer. -->
  <!-- NOTE: What follows is a nonphysical profile -->
  <!-- (limited number of layers with perfect material contrast) -->
  <!-- solely used fror illustration purposes to speed up the calculations. -->
  
  <layer mixfraction="1"/>
  <layer mixfraction="1"/>
  <layer mixfraction="0"/>
  <layer mixfraction="0"/>
  <layer mixfraction="0"/>
  <layer mixfraction="0"/>
  <layer mixfraction="0"/>
  <layer mixfraction="0"/>
  <layer mixfraction="0"/>
  <layer mixfraction="0"/>

  <!-- OPTIONAL. Specifies directory for writing HDF5 file. -->
  <!-- Will be determined automatically when omitted. -->
  <!-- (Name of HDF5 file is always created automatically.) -->
  <!-- Directory is relative to current work directory. -->
  <target directory="../InGaAs_superlattice"/>

</superlattice>

superlattice_builder_example2.xml : realistic InAs/GaAs superlattice

<!-- Example definition of a binary superlattice. -->

<superlattice>

  <!-- OPTIONAL. Specifies path to repository containing folders with force constants. -->
  <!-- Equals the current work directory when omitted. -->
  <materials_repository root_directory=".."/>

  <!-- Specify desired number of divisions for wavevector grid. -->
  <!-- Applies to both components of the superlattice. -->
  <gridDensity A="8" B="8" C="8"/>

  <!-- Main axis of the superlattice. -->
  <!-- na, nb, and nc (integers) specify the direction. -->
  <!-- nqline specifies number of q points in the 1D Brillouin zone -->
  <!-- used to build the Green's Function. Should be odd and at least 501.-->
  <normal na="0" nb="1" nc="1" nqline="501"/>

  <!-- Specify both compound names within the repository. -->
  <compound name="GaAs"/>
  <compound name="InAs"/>

  <!-- OPTIONAL. If specified, do not deal with three-phonon processes. -->
  <!-- <skip3ph/> -->

  <!-- Specify the concentrations of the second compound in each layer. -->
  <!-- NOTE: This is a physics-based profile that properly accounts for -->
  <!--       natural In segregation during superlattice growth. -->
  <layer mixfraction="0.0000000000"/>
  <layer mixfraction="0.1563524998"/>
  <layer mixfraction="0.1250819998"/>
  <layer mixfraction="0.1000655999"/>
  <layer mixfraction="0.0800524799"/>
  <layer mixfraction="0.0640419839"/>
  <layer mixfraction="0.0512335871"/>
  <layer mixfraction="0.0409868697"/>
  <layer mixfraction="0.0327894958"/>
  <layer mixfraction="0.0262315966"/>
  <layer mixfraction="0.0209852773"/>
  <layer mixfraction="0.0167882218"/>
  <layer mixfraction="0.0134305775"/>
  <layer mixfraction="0.0107444620"/>
  <layer mixfraction="0.0085955696"/>
  <layer mixfraction="0.0068764557"/>
  <layer mixfraction="0.0055011645"/>
  <layer mixfraction="0.0044009316"/>
  <layer mixfraction="0.0035207453"/>
  <layer mixfraction="0.0028165962"/>
  <layer mixfraction="0.0022532770"/>
  <layer mixfraction="0.0018026216"/>
  <layer mixfraction="0.0014420973"/>
  <layer mixfraction="0.0011536778"/>
  <layer mixfraction="0.0009229423"/>
  <layer mixfraction="0.0007383538"/>
  <layer mixfraction="0.0005906830"/>
  <layer mixfraction="0.0004725464"/>
  <layer mixfraction="0.0003780371"/>
  <layer mixfraction="0.0003024297"/>
  <layer mixfraction="0.0002419438"/>
  <layer mixfraction="0.0001935550"/>
  <layer mixfraction="0.0001548440"/>
  <layer mixfraction="0.0001238752"/>
  <layer mixfraction="0.0000991002"/>
  <layer mixfraction="0.0000792801"/>

  <!-- OPTIONAL. Specifies directory for writing HDF5 file. -->
  <!-- Will be determined automatically when omitted. -->
  <!-- (Name of HDF5 file is always created automatically.) -->
  <!-- Directory is relative to current work directory. -->
  <target directory="../InGaAs_superlattice"/>

</superlattice>

superlattice_builder_example3.xml : realistic Si/Ge superlattice

<!-- Example definition of a binary superlattice. -->

<superlattice>

  <!-- OPTIONAL. Specifies path to repository containing folders with force constants. -->
  <!-- Equals the current work directory when omitted. -->
  <materials_repository root_directory=".."/>

  <!-- Specify desired number of divisions for wavevector grid. -->
  <!-- Applies to both components of the superlattice. -->
  <gridDensity A="8" B="8" C="8"/>

  <!-- Main axis of the superlattice. -->
  <!-- na, nb, and nc (integers) specify the direction. -->
  <!-- nqline specifies number of q points in the 1D Brillouin zone -->
  <!-- used to build the Green's Function. Should be odd and at least 501.-->
  <normal na="0" nb="1" nc="1" nqline="501"/>

  <!-- Specify both compound names within the repository. -->
  <compound name="Si"/>
  <compound name="Ge"/>

  <!-- Specify the concentrations of the second compound in each layer. -->
  <layer mixfraction="0.009649"/>
  <layer mixfraction="0.009332"/>
  <layer mixfraction="0.009029"/>
  <layer mixfraction="0.008741"/>
  <layer mixfraction="0.008467"/>
  <layer mixfraction="0.008205"/>
  <layer mixfraction="0.007955"/>
  <layer mixfraction="0.007716"/>
  <layer mixfraction="0.007487"/>
  <layer mixfraction="0.007267"/>
  <layer mixfraction="0.007058"/>
  <layer mixfraction="0.006856"/>
  <layer mixfraction="0.006663"/>
  <layer mixfraction="0.006476"/>
  <layer mixfraction="0.006298"/>
  <layer mixfraction="0.006126"/>
  <layer mixfraction="0.005960"/>
  <layer mixfraction="0.005800"/>
  <layer mixfraction="0.005647"/>
  <layer mixfraction="0.005498"/>
  <layer mixfraction="0.005356"/>
  <layer mixfraction="0.005218"/>
  <layer mixfraction="0.005085"/>
  <layer mixfraction="0.025507"/>
  <layer mixfraction="0.032527"/>
  <layer mixfraction="0.021679"/>
  <layer mixfraction="0.020506"/>
  <layer mixfraction="0.019440"/>
  <layer mixfraction="0.018466"/>
  <layer mixfraction="0.017573"/>
  <layer mixfraction="0.016750"/>
  <layer mixfraction="0.015991"/>
  <layer mixfraction="0.015288"/>
  <layer mixfraction="0.014635"/>
  <layer mixfraction="0.014026"/>
  <layer mixfraction="0.013458"/>
  <layer mixfraction="0.012927"/>
  <layer mixfraction="0.012428"/>
  <layer mixfraction="0.011959"/>
  <layer mixfraction="0.011517"/>
  <layer mixfraction="0.011101"/>
  <layer mixfraction="0.010708"/>
  <layer mixfraction="0.010336"/>
  <layer mixfraction="0.009983"/>
  <layer mixfraction="0.009649"/>
  <layer mixfraction="0.009332"/>
  <layer mixfraction="0.009029"/>
  <layer mixfraction="0.008741"/>
  <layer mixfraction="0.008467"/>
  <layer mixfraction="0.008205"/>
  <layer mixfraction="0.007955"/>
  <layer mixfraction="0.007716"/>
  <layer mixfraction="0.007487"/>
  <layer mixfraction="0.007267"/>
  <layer mixfraction="0.007058"/>
  <layer mixfraction="0.006856"/>
  <layer mixfraction="0.006663"/>
  <layer mixfraction="0.006476"/>
  <layer mixfraction="0.006298"/>
  <layer mixfraction="0.006126"/>
  <layer mixfraction="0.005960"/>
  <layer mixfraction="0.005800"/>
  <layer mixfraction="0.005647"/>
  <layer mixfraction="0.005498"/>
  <layer mixfraction="0.005356"/>
  <layer mixfraction="0.005218"/>
  <layer mixfraction="0.005085"/>
  <layer mixfraction="0.025507"/>
  <layer mixfraction="0.032527"/>

  <!-- OPTIONAL. Specifies directory for writing HDF5 file. -->
  <!-- Will be determined automatically when omitted. -->
  <!-- (Name of HDF5 file is always created automatically.) -->
  <!-- Directory is relative to current work directory. -->
  <target directory="../SiGe_superlattice"/>

</superlattice>

Example input file for kappa_Tsweep

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kappa_Tsweep_example.xml : Obtain thermal conductivities and heat capacity of Si over a linear temperature sweep.

<Tsweep>

  <!-- OPTIONAL. Specifies path to H5 repository. -->
  <!-- Equals the launch directory when omitted. -->
  <H5repository root_directory=".."/>

  <!-- Specifies material information. -->
  <!-- Directory is relative to H5 repository directory. -->
  <compound directory="Si" base="Si" gridA="12" gridB="12" gridC="12"/>

  <!-- Specifies temperature sweep. Type can be "log" or "lin". -->
  <sweep type="lin" start="100" stop="1000" points="10"/>

  <!-- OPTIONAL. Axis along which to compute conductivities. -->
  <!-- Program will output tensor elements when axis is omitted. -->
  <transportAxis x="0" y="0" z="1"/>

  <!-- OPTIONAL. Obtains full BTE conductivities in addition to RTA solutions -->
  <!--           by solving linear system either iteratively or directly. -->
  <fullBTE iterative="true"/>

  <!-- OPTIONAL. Outputs heat capacities in addition to conductivities. -->
  <outputHeatCapacity/>

  <!-- OPTIONAL. Specifies desired location for writing output. -->
  <!-- When omitted, directory and file names will be created automatically. -->
  <!-- Directory is relative to launch directory. -->
  <target directory="examples_output/kappa_Tsweep/Si" file="AUTO"/>

</Tsweep>

Plotting the outputs generated by this example produces the following:


Example input file for cumulativecurves

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cumulativecurves_example.xml : Resolve Si thermal conductivity and heat capacity by various phonon metrics.

<cumulativecurves>

  <!-- OPTIONAL. Specifies path to H5 repository. -->
  <!-- Equals the launch directory when omitted. -->
  <H5repository root_directory=".."/>

  <!-- Specifies material information. -->
  <!-- Directory is relative to H5 repository directory. -->
  <compound directory="Si" base="Si" gridA="12" gridB="12" gridC="12"/>

  <!-- Cartesian vector along which to resolve conductivity. -->
  <transportAxis x="0" y="0" z="1"/>

  <!-- Select desired quantities -->
  <output conductivity="true" capacity="true"/>

  <!-- Select desired independent variables. -->
  <!-- MFP = mean free path; projMFP = MFP measured along transport axis; -->
  <!-- RT = relaxation time; freq = frequency (nu); -->
  <!-- angfreq = angular frequency (omega); energy = h*nu = hbar*omega -->
  <resolveby MFP="true" projMFP="true" RT="true" freq="true" angfreq="true" energy="true"/>

  <!-- OPTIONAL. Specifies number of points in each curve. (Default = 500). -->
  <optionalsettings curvepoints="500"/>

  <!-- OPTIONAL. Specifies desired directory for writing output. -->
  <!-- When omitted, directory will be created automatically. -->
  <!-- (Filenames are always generated automatically.) -->
  <!-- Directory is relative to launch directory. -->
  <target directory="examples_output/cumulativecurves/Si"/>

</cumulativecurves>

Plotting selected outputs generated by running this example without optional arguments (ambient temperature set at 300K) produces the following:


Example input file for kappa_crossplanefilms

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kappa_crossplanefilms_example.xml : Determine values and compact parametric form for cross-plane conductivity in In0.53Ga0.47As films.

<crossplanefilmsweep>

  <!-- OPTIONAL. Specifies path to H5 repository. -->
  <!-- Equals the launch directory when omitted. -->
  <H5repository root_directory=".."/>

  <!-- Specifies material information. -->
  <!-- Directory is relative to H5 repository directory. -->
  <compound directory="InGaAs" base="In0.53Ga0.47As" gridA="12" gridB="12" gridC="12"/>

  <!-- Specifies sweep of film thicknesses. Type can be "log" or "lin". -->
  <sweep type="log" start="1e-9" stop="1e-4" points="51"/>

  <!-- Cartesian vector along the film normal. -->
  <transportAxis x="0" y="0" z="1"/>

  <!-- OPTIONAL. Determines parametric analytic form for cross-plane conductivity. -->
  <obtainCompactModel/>

  <!-- OPTIONAL. Specifies desired location for writing output. -->
  <!-- When omitted, directory and file names will be created automatically. -->
  <!-- Directory is relative to launch directory. -->
  <target directory="examples_output/kappa_crossplanefilms/InGaAs" file="AUTO"/>

</crossplanefilmsweep>

Example input file for kappa_inplanefilms

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kappa_inplanefilms_example.xml : Determine values for in-plane conductivity in In0.53Ga0.47As films.

<inplanefilmsweep>

  <!-- OPTIONAL. Specifies path to H5 repository. -->
  <!-- Equals the launch directory when omitted. -->
  <H5repository root_directory=".."/>

  <!-- Specifies material information. -->
  <!-- Directory is relative to H5 repository directory. -->
  <compound directory="InGaAs" base="In0.53Ga0.47As" gridA="12" gridB="12" gridC="12"/>

  <!-- Specifies sweep of film thicknesses. Type can be "log" or "lin". -->
  <sweep type="log" start="1e-9" stop="1e-4" points="51"/>

  <!-- Cartesian vector along which the conductivity should be computed. -->
  <transportAxis x="1" y="0" z="0"/>

  <!-- Cartesian vector describing the film normal. -->
  <!-- Must be orthogonal to transportAxis. -->
  <normalAxis x="0" y="0" z="1"/>

  <!-- OPTIONAL. Sets specularity of film boundaries. -->
  <!-- Default value is 0, meaning fully diffuse boundary scattering. -->
  <specularity value="0.2"/>

  <!-- OPTIONAL. Specifies desired location for writing output. -->
  <!-- When omitted, directory and file names will be created automatically. -->
  <!-- Directory is relative to launch directory. -->
  <target directory="examples_output/kappa_inplanefilms/InGaAs" file="AUTO"/>

</inplanefilmsweep>

Plotting selected outputs generated by running the kappa_crossplanefilms and kappa_inplanefilms examples without optional argument (ambient temperature set at 300K) produces the following:

Example input files for steady_montecarlo1d

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steady_montecarlo1d_example1.xml : Obtain temperature profile inside Si thin film.

<!-- Illustrates Monte Carlo simulation of single layer structure. -->

<materials>

  <!-- OPTIONAL. Specifies path to H5 repository. -->
  <!-- Equals the current work directory when omitted. -->
  <H5repository root_directory=".."/>

  <!-- Specify information of all materials to be used in the simulation. -->
  <!-- Directory is relative to H5 repository directory. -->
  <material label="pureSi" directory="Si" compound="Si" gridA="12" gridB="12" gridC="12"/>

</materials>

<layers>

  <!-- Construct layer structure using the materials above. -->
  <!-- The index (starting from 1) specifies the order from "top" to "bottom". --> 
  <!-- Thicknesses are expressed in nm. -->
  <layer label="Si_slab" index="1" material="pureSi" thickness="200.0"/>

</layers>

<simulation>

  <!-- Set temperature differential, number of particles, and number of space bins. -->
  <!-- Reservoirs are set to Ttop = Tref + deltaT/2, Tbottom = Tref - deltaT/2. -->
  <!-- The reference temperature Tref is supplied as command line argument. -->
  <core deltaT="2.0" particles="1e6" bins="200"/>

  <!-- Set cartesian vector that describes the normal to the layer structure. -->
  <transportAxis x="0" y="0" z="1"/>

  <!-- OPTIONAL. Specifies location where to write temperature profiles. -->
  <!--           Directory is relative to current work directory. -->
  <target directory="examples_output/steady_montecarlo1d/example1"/>

</simulation>

Running this example without optional argument (ambient temperature set at 300K) produced the following results. Note that numerical values will slightly vary each trial due to the inherently stochastic nature of Monte Carlo simulations.

basicproperties_300K.txt

LAYER 1 pureSi (200 nm)
T_TOP 301 K
T_BOTTOM 299 K
T_REF 300 K
N_PARTICLES 1000000
HEAT_FLUX 533.53 MW/m^2
HEAT_FLUX_TOLERANCE 772.746 kW/m^2
EFF_CONDUCTIVITY 53.353 W/m-K
EFF_CONDUCTIVITY_TOLERANCE 0.0772746 W/m-K
EFF_RESISTIVITY 3.74862 nK-m^2/W
EFF_CONDUCTANCE 266.765 MW/K-m^2


steady_montecarlo1d_example2.xml : Obtain temperature profile inside Si/Ge/Si structure.

<!-- Illustrates Monte Carlo simulation of multilayer structure. -->

<materials>

  <!-- OPTIONAL. Specifies path to H5 repository. -->
  <!-- Equals the current work directory when omitted. -->
  <H5repository root_directory=".."/>

  <!-- Specify information of all materials to be used in the simulation. -->
  <!-- Directory is relative to H5 repository directory. -->
  <material label="pureSi" directory="Si" compound="Si" gridA="12" gridB="12" gridC="12"/>
  <material label="pureGe" directory="Ge" compound="Ge" gridA="12" gridB="12" gridC="12"/>

</materials>

<layers>

  <!-- Construct layer structure using the materials above. -->
  <!-- The index (starting from 1) specifies the order from "top" to "bottom". -->
  <!-- Thicknesses are expressed in nm. -->
  <layer label="cap" index="1" material="pureSi" thickness="100.0"/>
  <layer label="device" index="2" material="pureGe" thickness="100.0"/>
  <layer label="substrate" index="3" material="pureSi" thickness="100.0"/>

</layers>

<simulation>

  <!-- Set temperature differential, number of particles, and number of space bins. -->
  <!-- Reservoirs are set to Ttop = Tref + deltaT/2, Tbottom = Tref - deltaT/2. -->
  <!-- The reference temperature Tref is supplied as command line argument. -->
  <core deltaT="2.0" particles="1e6" bins="300"/>

  <!-- Set cartesian vector that describes the normal to the layer structure. -->
  <transportAxis x="0" y="0" z="1"/>

  <!-- OPTIONAL. Specifies location where to write temperature profiles. -->
  <!--           Directory is relative to current work directory. -->
  <target directory="examples_output/steady_montecarlo1d/example2"/>

</simulation>

Running this example without optional argument (ambient temperature set at 300K) produced the following results. Note that numerical values will slightly vary each trial due to the inherently stochastic nature of Monte Carlo simulations.

basicproperties_300K.txt

LAYER 1 pureSi (100 nm)
LAYER 2 pureGe (100 nm)
LAYER 3 pureSi (100 nm)
T_TOP 301 K
T_BOTTOM 299 K
T_REF 300 K
N_PARTICLES 1000000
HEAT_FLUX 102.881 MW/m^2
HEAT_FLUX_TOLERANCE 242.053 kW/m^2
EFF_CONDUCTIVITY 15.4321 W/m-K
EFF_CONDUCTIVITY_TOLERANCE 0.036308 W/m-K
EFF_RESISTIVITY 19.4399 nK-m^2/W
EFF_CONDUCTANCE 51.4405 MW/K-m^2


steady_montecarlo1d_example3.xml : Obtain temperature profile and spectral heat flux (resolved by phonon angular frequency) inside Si/Ge/Si structure.

<!-- Illustrates capabilities for resolving spectral heat flux. -->

<materials>

  <!-- OPTIONAL. Specifies path to H5 repository. -->
  <!-- Equals the current work directory when omitted. -->
  <H5repository root_directory=".."/>

  <!-- Specify information of all materials to be used in the simulation. -->
  <!-- Directory is relative to H5 repository directory. -->
  <material label="pureSi" directory="Si" compound="Si" gridA="12" gridB="12" gridC="12"/>
  <material label="pureGe" directory="Ge" compound="Ge" gridA="12" gridB="12" gridC="12"/>

</materials>

<layers>

  <!-- Construct layer structure using the materials above. -->
  <!-- The index (starting from 1) specifies the order from "top" to "bottom". -->
  <!-- Thicknesses are expressed in nm. -->
  <layer label="cap" index="1" material="pureSi" thickness="100.0"/>
  <layer label="device" index="2" material="pureGe" thickness="100.0"/>
  <layer label="substrate" index="3" material="pureSi" thickness="100.0"/>

</layers>

<simulation>

  <!-- Set temperature differential, number of particles, and number of space bins. -->
  <!-- Reservoirs are set to Ttop = Tref + deltaT/2, Tbottom = Tref - deltaT/2. -->
  <!-- The reference temperature Tref is supplied as command line argument. -->
  <core deltaT="2.0" particles="1e5" bins="300"/>

  <!-- Set cartesian vector that describes the normal to the layer structure. -->
  <transportAxis x="0" y="0" z="1"/>

  <!-- OPTIONAL. Specifies location where to write temperature profiles. -->
  <!--           Directory is relative to current work directory. -->
  <target directory="examples_output/steady_montecarlo1d/example3"/>

</simulation>

<spectralflux>
    
    <!-- Set number of phonon frequency bins -->
    <resolution frequencybins="200"/>

    <!-- Illustrates syntax to manually add locations at which the flux should be resolved -->
    <!-- <location position="50"/> -->
    <!-- <location position="150"/> -->
    <!-- <location position="250"/> -->

    <!-- Add a range of locations at which the flux should be resolved -->
    <!-- Locations are expressed in nm. -->
    <locationrange start="1" stop="299" step="1"/>
    
</spectralflux>

Running this example without optional argument (ambient temperature set at 300K) produced the following results. Note that numerical values will slightly vary each trial due to the inherently stochastic nature of Monte Carlo simulations.

basicproperties_300K.txt

LAYER 1 pureSi (100 nm)
LAYER 2 pureGe (100 nm)
LAYER 3 pureSi (100 nm)
T_TOP 301 K
T_BOTTOM 299 K
T_REF 300 K
N_PARTICLES 100000
HEAT_FLUX 102.18 MW/m^2
HEAT_FLUX_TOLERANCE 1.56173 MW/m^2
EFF_CONDUCTIVITY 15.327 W/m-K
EFF_CONDUCTIVITY_TOLERANCE 0.23426 W/m-K
EFF_RESISTIVITY 19.5734 nK-m^2/W
EFF_CONDUCTANCE 51.0899 MW/K-m^2


make_colormap.m : matlab / octave script for visualising the spectral heat flux across space as a colormap.

%Declare some variables

Nspace = 299;
Nbins = 200;
spacegrid = linspace(1,299,Nspace);
spaceunit = 'nm';
omegagrid = zeros(Nbins);
flux = zeros(Nbins,Nspace);
flux_plot = zeros(Nbins,Nspace);

%Read csv files

for nsurf=1:Nspace

  file = strcat('spectralflux_surface_',num2str(nsurf),'_300K.csv');
  disp(['Processing ' file]);
  fflush(stdout);
  data = csvread(file);
  flux(:,nsurf) = flipud(data(2:end,2));

  if(nsurf==1)
    omegagrid = flipud(data(2:end,1));
  endif

endfor

%Obtain color tables

figure;
imagesc(spacegrid,omegagrid,zeros(Nbins,Nspace));
colormap(jet)
colordata_buffer = colormap;
colordata_plus = colordata_buffer(1:56,1:3);
colormap(copper)
colordata_buffer = flipud(colormap);
colordata_minus = colordata_buffer(1:56,1:3);
close;

%Determine largest positive and negative heat fluxes

qmax = max(max(flux));
qmin = min(min(flux));
disp(['qmax = ' num2str(qmax)]);
disp(['qmin = ' num2str(qmin)]);

%Make rescaled versions of positive and negative data

for nrow=1:size(flux,1)
 for ncol=1:size(flux,2)
  if(flux(nrow,ncol)>=0) flux_plot(nrow,ncol) = flux(nrow,ncol)/qmax; endif
  if(flux(nrow,ncol)<0) flux_plot(nrow,ncol) = -abs(flux(nrow,ncol))/abs(qmin); endif
 endfor
endfor

% Make plot

imagesc(spacegrid,omegagrid,flux_plot);
set(gca,'Ydir','normal');
caxis([-1 1]);
colormap([colordata_minus;[0 0 0];colordata_plus]);
colorbar;
set(gca,'Fontsize',16);
xlabel(strcat('position [',spaceunit,']'));
ylabel('phonon frequency [rad/ps]');
saveas(gca,'colorplot.png');

Example input files for steady_montecarlo1d_powersource

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steady_montecarlo1d_powermap_example1.xml : Obtain temperature profile inside Si thin film.

<!-- Illustrates Monte Carlo simulation of single layer structure. -->

<materials>

  <!-- OPTIONAL. Specifies path to H5 repository. -->
  <!-- Equals the current work directory when omitted. -->
  <H5repository root_directory=".."/>

  <!-- Specify information of all materials to be used in the simulation. -->
  <!-- Directory is relative to H5 repository directory. -->
  <material label="pureSi" directory="Si" compound="Si" gridA="12" gridB="12" gridC="12"/>

</materials>

<layers>

  <!-- Construct layer structure using the materials above. -->
  <!-- The index (starting from 1) specifies the order from "top" to "bottom". --> 
  <!-- Thicknesses are expressed in nm. -->
  <layer label="Si_slab" index="1" material="pureSi" thickness="200.0"/>

</layers>

<simulation>

  <!-- Set ambient temperature, power density [W/m^2] of the source, -->
  <!-- number of particles and number of space bins. -->
  <core Tambient="300.0" powerdensity="1e8" particles="1e5" bins="200"/>

  <!-- Set cartesian vector that describes the normal to the layer structure. -->
  <transportAxis x="0" y="0" z="1"/>

  <!-- OPTIONAL. Specifies location where to write temperature profiles. -->
  <!--           Directory is relative to current work directory. -->
  <target directory="examples_output/steady_montecarlo1d_powersource/example1"/>

</simulation>

Running this example without optional argument (ambient temperature set at 300K) produced the following results. Note that numerical values will slightly vary each trial due to the inherently stochastic nature of Monte Carlo simulations.

basicproperties_300K.txt

LAYER 1 pureSi (200 nm)
T_AMBIENT 300 K
SOURCE_DISSIPATION 100 MW/m^2
N_PARTICLES 100000
DELTAT_SOURCE 0.398035 K
DELTAT_SOURCE_TOLERANCE 0.00190553 K
EFF_CONDUCTIVITY 50.2515 W/m-K
EFF_CONDUCTIVITY_TOLERANCE 0.240278 W/m-K
EFF_RESISTIVITY 3.97998 nK-m^2/W
EFF_CONDUCTANCE 251.257 MW/K-m^2


steady_montecarlo1d_powersource_example2.xml : Obtain temperature profile inside Si/Ge/Si structure.

<!-- Illustrates Monte Carlo simulation of multilayer structure. -->

<materials>

  <!-- OPTIONAL. Specifies path to H5 repository. -->
  <!-- Equals the current work directory when omitted. -->
  <H5repository root_directory=".."/>

  <!-- Specify information of all materials to be used in the simulation. -->
  <!-- Directory is relative to H5 repository directory. -->
  <material label="pureSi" directory="Si" compound="Si" gridA="12" gridB="12" gridC="12"/>
  <material label="pureGe" directory="Ge" compound="Ge" gridA="12" gridB="12" gridC="12"/>

</materials>

<layers>

  <!-- Construct layer structure using the materials above. -->
  <!-- The index (starting from 1) specifies the order from "top" to "bottom". -->
  <!-- Thicknesses are expressed in nm. -->
  <layer label="cap" index="1" material="pureSi" thickness="100.0"/>
  <layer label="device" index="2" material="pureGe" thickness="100.0"/>
  <layer label="substrate" index="3" material="pureSi" thickness="100.0"/>

</layers>

<simulation>

<!-- Set ambient temperature, power density [W/m^2] of the source, -->
<!-- number of particles and number of space bins. -->
<core Tambient="300.0" powerdensity="1e8" particles="1e5" bins="200"/>

  <!-- Set cartesian vector that describes the normal to the layer structure. -->
  <transportAxis x="0" y="0" z="1"/>

  <!-- OPTIONAL. Specifies location where to write temperature profiles. -->
  <!--           Directory is relative to current work directory. -->
  <target directory="examples_output/steady_montecarlo1d_powersource/example2"/>

</simulation>

Running this example without optional argument (ambient temperature set at 300K) produced the following results. Note that numerical values will slightly vary each trial due to the inherently stochastic nature of Monte Carlo simulations.

basicproperties_300K.txt

LAYER 1 pureSi (100 nm)
LAYER 2 pureGe (100 nm)
LAYER 3 pureSi (100 nm)
T_AMBIENT 300 K
SOURCE_DISSIPATION 100 MW/m^2
N_PARTICLES 100000
DELTAT_SOURCE 1.98269 K
DELTAT_SOURCE_TOLERANCE 0.00656331 K
EFF_CONDUCTIVITY 15.1316 W/m-K
EFF_CONDUCTIVITY_TOLERANCE 0.0500762 W/m-K
EFF_RESISTIVITY 19.8261 nK-m^2/W
EFF_CONDUCTANCE 50.4387 MW/K-m^2


steady_montecarlo1d_powersource_example3.xml : Obtain temperature profile and spectral heat flux (resolved by phonon angular frequency) inside Si/Ge/Si structure.

<!-- Illustrates capabilities for resolving spectral heat flux. -->

<materials>

  <!-- OPTIONAL. Specifies path to H5 repository. -->
  <!-- Equals the current work directory when omitted. -->
  <H5repository root_directory=".."/>

  <!-- Specify information of all materials to be used in the simulation. -->
  <!-- Directory is relative to H5 repository directory. -->
  <material label="pureSi" directory="Si" compound="Si" gridA="12" gridB="12" gridC="12"/>
  <material label="pureGe" directory="Ge" compound="Ge" gridA="12" gridB="12" gridC="12"/>

</materials>

<layers>

  <!-- Construct layer structure using the materials above. -->
  <!-- The index (starting from 1) specifies the order from "top" to "bottom". -->
  <!-- Thicknesses are expressed in nm. -->
  <layer label="cap" index="1" material="pureSi" thickness="100.0"/>
  <layer label="device" index="2" material="pureGe" thickness="100.0"/>
  <layer label="substrate" index="3" material="pureSi" thickness="100.0"/>

</layers>

<simulation>

<!-- Set ambient temperature, power density [W/m^2] of the source, -->
<!-- number of particles and number of space bins. -->
<core Tambient="300.0" powerdensity="1e8" particles="1e4" bins="200"/>

  <!-- Set cartesian vector that describes the normal to the layer structure. -->
  <transportAxis x="0" y="0" z="1"/>

  <!-- OPTIONAL. Specifies location where to write temperature profiles. -->
  <!--           Directory is relative to current work directory. -->
  <target directory="examples_output/steady_montecarlo1d_powersource/example3"/>

</simulation>

<spectralflux>
    
    <!-- Set number of phonon frequency bins -->
    <resolution frequencybins="200"/>

    <!-- Illustrates syntax to manually add locations at which the flux should be resolved -->
    <!-- <location position="50"/> -->
    <!-- <location position="150"/> -->
    <!-- <location position="250"/> -->

    <!-- Add a range of locations at which the flux should be resolved -->
    <!-- Locations are expressed in nm. -->
    <locationrange start="1" stop="299" step="1"/>
    
</spectralflux>

Running this example without optional argument (ambient temperature set at 300K) produced the following results. Note that numerical values will slightly vary each trial due to the inherently stochastic nature of Monte Carlo simulations.

basicproperties_300K.txt

LAYER 1 pureSi (100 nm)
LAYER 2 pureGe (100 nm)
LAYER 3 pureSi (100 nm)
T_AMBIENT 300 K
SOURCE_DISSIPATION 100 MW/m^2
N_PARTICLES 10000
DELTAT_SOURCE 1.93148 K
DELTAT_SOURCE_TOLERANCE 0.0276022 K
EFF_CONDUCTIVITY 15.5452 W/m-K
EFF_CONDUCTIVITY_TOLERANCE 0.229505 W/m-K
EFF_RESISTIVITY 19.2985 nK-m^2/W
EFF_CONDUCTANCE 51.8175 MW/K-m^2

Example input file for transient_analytic1d

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transient_analytic1d_example.xml : Determine temperature profiles at specific times and transient evolution of source response and MSD for single-pulse input in In0.53Ga0.47As.

<analytic1d>

  <!-- OPTIONAL. Specifies path to H5 repository. -->
  <!-- Equals the current work directory when omitted. -->
  <H5repository root_directory=".."/>

  <!-- Specifies material information. -->
  <!-- Directory is relative to H5 repository directory. -->
  <compound directory="InGaAs" base="In0.53Ga0.47As" gridA="12" gridB="12" gridC="12"/>

  <!-- Cartesian vector describing the thermal transport axis. -->
  <transportAxis x="0" y="0" z="1"/>

  <!-- Computes single pulse response T(x,t) versus space and time. -->
  <!-- The program will automatically choose an adaptive spatial grid. -->
  <!-- This example illustrates user-provided timelist functionality. -->
  <spacecurves spacepoints = "500" timepoints="{10e-9,30e-9,100e-9,300e-9,1e-6,3e-6,10e-6}"/>
  
  <!-- Alternatively, the program also supports automatic generation of timepoints. -->
  <!-- timesweep can be "log" or "lin". -->
  <!-- spacecurves spacepoints = "500" timesweep="log" tstart="10e-9" tstop="10e-6" timepoints="10"/>

  <!-- Computes temperature T(x=0) at the heat source versus time. -->
  <!-- timesweep can be "log" or "lin". -->
  <sourcetransient timesweep="log" tstart="1e-9" tstop="1e-4" points="101"/>

  <!-- Computes mean square displacement of thermal energy versus time. -->
  <!-- timesweep can be "log" or "lin". -->
  <MSD timesweep="log" tstart="1e-12" tstop="1e-6" points="121"/>

  <!-- OPTIONAL. Specifies desired directory for writing output. -->
  <!-- When omitted, directory will be created automatically. -->
  <!-- (Filenames are always created automatically.) -->
  <!-- Directory is relative to current work directory. -->
  <target directory="examples_output/transient_analytic1d/In0.53Ga0.47As"/>

</analytic1d>

Plotting selected output produced by running this example without optional argument (ambient temperature set at 300K) yields the following.