Besides the routine inputs in CONTROL file of ShengBTE, FourPhonon requires a fourth-order force constants and some new name-lists in CONTROL file. Check ShengBTE website for definition of other name-lists.

Parallel environment

Version 1.1 and 1.0 were written for MPI parallelism. Starting from Version 1.2 that supports iterative solver for four-phonon scattering, we have migrated to OpenMP to handle large memory required for this iterative solver. In the future we may support MPI+OpenMP hybrid parallelism to allow more flexibility. Make sure to add -qopenmp in compilation or:

export FFLAGS=-qopenmp -traceback -debug -O2 -static_intel

4th-IFCs files: FORCE_CONSTANTS_4TH

This file contains the fourth-order interatomic force constant matrix, and uses a sparse description to save space. To construct 4th-IFCs, one can refer to the Fourthorder python scripts. The format of this force constants is a direct extension of third-order force constants, and contains nb blocks of such matrix:

• A blank line
• A 1-based sequential index (from 1 to nb)
• A line with the Cartesian coordinates of the second unit cell in Å
• A line with the Cartesian coordinates of the third unit cell in Å
• A line with the Cartesian coordinates of the fourth unit cell in Å
• A line with the 1-based indices of the four atoms involved, each from 1 to natoms
• 81 lines of force constant matrix in $\frac{\textrm{eV}}{\textrm{Å}^4}$. The indexes at the beginning label the Cartesian axes.

An example block of this file:

1
0.0000000000e+00 0.0000000000e+00 0.0000000000e+00
0.0000000000e+00 0.0000000000e+00 0.0000000000e+00
0.0000000000e+00 0.0000000000e+00 0.0000000000e+00
     1      1      1      1
 1  1  1  1       -42.0002584218
 1  1  1  2         0.0000000000
 1  1  1  3         0.0000000000
 1  1  2  1         0.0000000000
 1  1  2  2        40.3875689003
 1  1  2  3         0.0000000000
 1  1  3  1         0.0000000000
 1  1  3  2         0.0000000000
 1  1  3  3        40.3875689003
 1  2  1  1         0.0000000000
 1  2  1  2        40.3875689003
 1  2  1  3         0.0000000000
 1  2  2  1        40.3875689003
 1  2  2  2         0.0000000000
 1  2  2  3         0.0000000000
 1  2  3  1         0.0000000000
 1  2  3  2         0.0000000000
 1  2  3  3         0.0000000000
 1  3  1  1         0.0000000000
 1  3  1  2         0.0000000000
 1  3  1  3        40.3875689003
 1  3  2  1         0.0000000000
 1  3  2  2         0.0000000000
 1  3  2  3         0.0000000000
 1  3  3  1        40.3875689003
 1  3  3  2         0.0000000000
 1  3  3  3         0.0000000000
 2  1  1  1         0.0000000000
 2  1  1  2        40.3875689003
 2  1  1  3         0.0000000000
 2  1  2  1        40.3875689003
 2  1  2  2         0.0000000000
 2  1  2  3         0.0000000000
 2  1  3  1         0.0000000000
 2  1  3  2         0.0000000000
 2  1  3  3         0.0000000000
 2  2  1  1        40.3875689003
 2  2  1  2         0.0000000000
 2  2  1  3         0.0000000000
 2  2  2  1         0.0000000000
 2  2  2  2       -42.0002584218
 2  2  2  3         0.0000000000
 2  2  3  1         0.0000000000
 2  2  3  2         0.0000000000
 2  2  3  3        40.3875689003
 2  3  1  1         0.0000000000
 2  3  1  2         0.0000000000
 2  3  1  3         0.0000000000
 2  3  2  1         0.0000000000
 2  3  2  2         0.0000000000
 2  3  2  3        40.3875689003
 2  3  3  1         0.0000000000
 2  3  3  2        40.3875689003
 2  3  3  3         0.0000000000
 3  1  1  1         0.0000000000
 3  1  1  2         0.0000000000
 3  1  1  3        40.3875689003
 3  1  2  1         0.0000000000
 3  1  2  2         0.0000000000
 3  1  2  3         0.0000000000
 3  1  3  1        40.3875689003
 3  1  3  2         0.0000000000
 3  1  3  3         0.0000000000
 3  2  1  1         0.0000000000
 3  2  1  2         0.0000000000
 3  2  1  3         0.0000000000
 3  2  2  1         0.0000000000
 3  2  2  2         0.0000000000
 3  2  2  3        40.3875689003
 3  2  3  1         0.0000000000
 3  2  3  2        40.3875689003
 3  2  3  3         0.0000000000
 3  3  1  1        40.3875689003
 3  3  1  2         0.0000000000
 3  3  1  3         0.0000000000
 3  3  2  1         0.0000000000
 3  3  2  2        40.3875689003
 3  3  2  3         0.0000000000
 3  3  3  1         0.0000000000
 3  3  3  2         0.0000000000
 3  3  3  3       -42.0002584218

Settings in CONTROL file

This CONTROL file contains all the user-specified settings and parameters, including crystal structural information, broadening factor, q-mesh, temperature, functions, etc.