mirror of https://gitlab.com/QEF/q-e.git
43 lines
2.4 KiB
Plaintext
43 lines
2.4 KiB
Plaintext
QHA package, by Eyvaz Isaev - For Quasi-Harmonic Approximation
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Executable files can be compiled using the Compile script:
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tetra.x - to generate vertexes of microtetrahedra
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matdyn.x - to generate phonons for microtetrahedra vertexes
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Partial_phonon_DOS.x - to project DOS onto a specified atom and its polarization vector
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phonon_dos.x - to calculate phonon DOS and atom projected phonon DOS.
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Ghost_DOS.x - to remove "NaN" statements (taken as (DOS(i-1)+DOS(i+1))/2) with small
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(order of 0.5THz) frequency step in integration
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Atom_projected_properties.x - to integrate phonon DOS, and atom projected DOS to find out
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atom-specific contribution to the zero point vibration energy, phonon DOS,
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vibration energy, specific heat, entropy, internal energy, as well as
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LO and TA (g_x,g_y,g_z) components of atom-specific phonon DOS
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NB!!! The limitation for the program is the presence of only one frequency gap in the phonon spectrum,
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i.e. the program assumes that there are well separated low-lying "acoustic" modes and optical branches.
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Hopefully will be corrected for more complex structures to avoid this limitation.
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Debye.x - calculates the Debye temperature
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F_QHA.x - Total vibrational energy, the specific heat, entropy and internal energy in the
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quasiharmonic approximation
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C_v is in units of R, the universal gas constant.
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If you like to see C_v or S in kcal/(mol K) or J/(mol K) then just multilply the 4th column
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by a factor of 2 (in kcal/(mol K)), or 8.31 ( in J/(mol K)), respectively.
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Presumably one needs to divide C_v to a number of formula units in the unit cell.
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Mean_Square_Displacements.x - calculates exactly what is declared (in Ang^2)
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To start phonon calculations one needs the following files:
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run_Phonon_DOS.sh - the main script - see the Examples directory for examples
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matdyn.init - to specify the force constants matrix and atomic masses
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ttrinp - Brillouin zone (tetrahedra) information
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There are predefined ttrinp files for simple cubic, face centered cubic,
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body centered cubic, hexagonal, simple tetragonal and simple orthorhombic
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lattices. For body centered tetragonal with c/a<1 there are instructions
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on how to setup ttrinp file (it is quite easy). Maybe the same "trick"
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can be applied for other structures with more complicated Brillouin zone.
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