LTEMPER
LTEMPER = [logical]
Default: LTEMPER = .FALSE.
Description: LTEMPER specified whether parallel tempering is used. The flag must be used in combination with IMAGES.
VASP supports various modes where simultaneous calculations for different INCAR, KPOINTS, POTCAR, or POSCAR files are performed. The parallel tempering mode is explained in this section, however, please read the section IMAGES first.
If the tags IMAGES=nn and LTEMPER=.TRUE. are set in the INCAR file, VASP performs parallel tempering calculations. In this case, it is expedient to supply different INCAR and POSCAR files in each subdirectory 01, 02, 03, ..., nn. For each subdiretory a different simulation temperature should be supplied using the tags TEBEG in the INCAR files 01/INCAR, 02/INCAR ... nn/INCAR.
In the course of the simulations, VASP will attempt to swap the temperatures between the images. Swapping attempts are made every NTEMPER MD steps. Information on the current temperatures for each image can be found in the OUTCAR file around the lines
parallel tempering new
The average acceptance ratios are also written to the OUTCAR file. For efficient parallel tempering the acceptance ratio should not fall much below 0.1. If the acceptance ratio is too small, one usually needs to increase the number of images.