Electron-phonon interactions from Monte-Carlo sampling: Difference between revisions
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It also involves phonon calculations for the <math>\Gamma</math> point (see {{TAG|Phonons from finite differences}}). So many tags in the {{TAG|INCAR}} will be used from the phonon calculations. | It also involves phonon calculations for the <math>\Gamma</math> point (see {{TAG|Phonons from finite differences}}). So many tags in the {{TAG|INCAR}} will be used from the phonon calculations. | ||
To enable electron-phonon interactions from MC methods {{TAG|PHON_LMC}}=''.TRUE.'' has to be set in the {{TAG|INCAR}} file. Also {{TAG|IBRION}}=6 has to be selected (the MC method is currently only implemented for {{TAG|IBRION}}=6). | |||
To enable electron-phonon interactions from MC methods {{TAG|PHON_LMC}}=''.TRUE.'' has to be set in the {{TAG|INCAR}} file. | |||
== Full MC sampling == | == Full MC sampling == | ||
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System = DEFAULT | System = DEFAULT | ||
PREC = Accurate | {{TAGBL|PREC}} = Accurate | ||
ISMEAR = 0; SIGMA = 0.1; | {{TAGBL|ISMEAR}} = 0; {{TAGBL|SIGMA}} = 0.1; | ||
IBRION = 6 | {{TAGBL|IBRION}} = 6 | ||
PHON_LMC = .TRUE. | {{TAGBL|PHON_LMC}} = .TRUE. | ||
PHON_NSTRUCT = 100 | {{TAGBL|PHON_NSTRUCT}} = 100 | ||
{{TAGBL|TEBEG}} = 0.0 | |||
== ZG configuration (one-shot sampling) | == ZG configuration (one-shot sampling) | ||
A sample {{TAG|INCAR}} file for the | A sample {{TAG|INCAR}} file for the | ||
Revision as of 10:07, 9 April 2019
Important: This feature will be only available from VASP6.0 or higher.
First of all this method needs a sufficiently large super cell. It also involves phonon calculations for the [math]\displaystyle{ \Gamma }[/math] point (see Phonons from finite differences). So many tags in the INCAR will be used from the phonon calculations.
To enable electron-phonon interactions from MC methods PHON_LMC=.TRUE. has to be set in the INCAR file. Also IBRION=6 has to be selected (the MC method is currently only implemented for IBRION=6).
Full MC sampling
The tag PHON_NSTRUCT sets the number of structures generated due to the MC sampling. Convergence of the observable with respect to this number should be monitored.
The tag TEBEG=0 is also needed to choose the temperature at which the sampling is run.
Additionally the PHON_LBOSE can be set .TRUE. or .FALSE. (default PHON_LBOSE=.TRUE.), which selects Bose-Einstein or Maxwell-Boltzmann statistics, respectively.
A sample INCAR file for 0 K looks like the following:
System = DEFAULT PREC = Accurate ISMEAR = 0; SIGMA = 0.1; IBRION = 6 PHON_LMC = .TRUE. PHON_NSTRUCT = 100 TEBEG = 0.0
== ZG configuration (one-shot sampling)
A sample INCAR file for the