Frequency Domain Perfectly Matched Layer (FDPML)

Introduction

FDPML is a computational method to simulate heat transport through nanostructured materials. The method converts atomistic equations of motion for every atom inside a simulation domain to a set of linear algebraic equations. The equations can then be solved using iterative solvers. The model is efficient as it stores the matrices in sparse format (COO), while also being able to be deployed across multiple cluster node.

For a more detailed mathematical description of the model please refer
kakodkar et. al. Journal of Applied Physics 118, 094301 (2015)

Installation

Dependencies

MPI
openmpi FORTRAN90 Compiler
IntelMKL

Clone this repository using git clone git@github.com:Rohit-Kakodkar/FDPML.git

Install using Makefile : make all

Upon installation execultables will be created in \bin folder

Usage

Overview

The method can be used to obtain 2 properties intrinsic to heat transport through nanostructured materials.

Transmission coefficient across interfaces- Please refer here
Scattering Cross-section due to nanoparticles- Please refer here

Input parameters for simulations are specified through input cards described below

All quantities whose dimensions are not explicitly specified are in RYDBERG ATOMIC UNITS. Charge is "number" charge (i.e. not multiplied by e); potentials are in energy units (i.e. they are multiplied by e).

Structure of the input data:

&filenames
	...
/
&system
	...
/
&postprocessing
	...
/
&plotting
	...
/

Detailed discription

Input cards:

filenames
- flfrc1 - force constant file of the matrix material (should be generated via Quantum espresso). NOT IN XML FORMAT
- flfrc2 - force constant file of impurity material (should be generated via Quantum espresso). NOT IN XML FORMAT
- mass_input - logical, if true masses are calculated with atomic resolution else masses are calculated based on supercell
- mass_file - mass domain file generated by gendomain.f90
- domain_file - domain specification generated by gendomain.f90
system
- simulation_type = 'interface' or 'nanoparticle'
- PD = size of the primary domain, should be same as the one generated gendomain.f90
- LPML = length of PML. Ignored if PML calculation is auto
- periodic = logical, if true applied periodic boundaries in x and y direction
- crystal_coordinates = logical, if true work in crystal coordinates
- asr = acoustic sum rule. Refer QE documentation
- wavetype = 'half' or 'full' to specify type of incident wave
- q = wavevector, ignored if mp = .true.
- mode = polarization
- sigmamax = maximum value of damping coefficient, Ignored if PML calculation is auto
- mp = generate qpoint list base Monkhorst Pack(MP) grid
- qpoint = n, then choose nth q from list of q generated by MP grid
- nk1, nk2, nk3 = k-spacings in x,y and z directions for MP grid
postprocessing
- calc_TC = logical, calculate transmission coefficient (for interface problems)
- calc_gam = logical, calculate scattering cross-section (for nanoparticle problems)
plotting
- plot_K = logical, plot variation of K vector on TD(3)/2 plane
- plot_uinc = logical, plot incident wave
- plot_uscat = logical, plot scattered wave
- plot_sig = logical, plot variation of damping coefficient
- plottingmode = 1, 2, or 3, plot x, y, or z components of above properties

Future improvements (In progress)

Incorporate anharmonic force constants while obtaining thermal properties
Calculate scattering rates from scattering cross-sections
Calculate density of phonon states to obtain thermal interface conductance from transmission coefficients

lujia/FDPML