I found that many of atomic forces are larger than 0.001 eV/A in case of supercell (SC, 4x4) while all forces in primitive cell (PC) is lower than 0.001 eV/A when I performed geomoetric optimization for PC and use the results for positional input in SC for single-point calculation.
The forces in SC are shown below.
...
-0.018383 0.005499 0.092023
0.000000 0.074965 -0.003715
0.362168 0.156719 0.295411
0.000000 -0.390551 1.259424
-0.362168 0.156719 0.295411
0.000000 0.250426 -0.006243
-0.070366 -0.110111 -0.166424
...
I used the same method except for k-point mesh (24x1x24 vs 6x1x6) for SC (4x1x4) and PC.
I don't know why such deviation occurred. How can I obtain the reasonable forces i SC using the positional result obtained from PC?
Best regards,
Young
FORCES in PC and SC
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Re: FORCES in PC and SC
The volume of the cell is a parameter of your calculation.
When you change it the results are also changed.
Going to larger cells makes the relaxation more difficult.
Use more severe relaxation criteria.
When you change it the results are also changed.
Going to larger cells makes the relaxation more difficult.
Use more severe relaxation criteria.