Dear Collegues,
I started a calculation by setting the tag
LVDW=.TRUE.
and looked into the total energy which differs almost like 16.4 eV from the calculation in which this tag is removed.
I don't think this is reasonable, and i do not know where i am going wrong.
Could you please help.
Here are some additional details.
Total Energy without Dispersion Correction = -1946.740941 eV
Total Energy With Dispersion Correction = -1962.968314 eV
From OUTCAR
Grimme's potential added to compensate for missing vdW interactions
-------------------------------------------------------------------
Parameters for Grimme's potential:
C6(Jnm^6/mol) R0(A)
-----------------------------
O 0.700 1.342
Si 9.230 1.716
C 1.750 1.452
^@^@ 0.000 0.000
H 0.140 1.001
Cutoff radius: 30.000 A
Global scaling factor: 0.750 A
Parameter d: 20.000 A
Number of pair interactions contributing to Grimme's potential: 427374
Estimated vdW energy (eV): -16.36075
I also did calculations by reducing the cutoff radius but that didn't help me too much..
Please help.
Major Total Energy Differences - Dispersion Correction
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Major Total Energy Differences - Dispersion Correction
Last edited by kmkumar on Thu Mar 31, 2011 10:56 am, edited 1 time in total.
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Major Total Energy Differences - Dispersion Correction
Get the Grimme papers, calculate one pair by hand and judge for yourself. Reason will come.
Cheers,
alex
Cheers,
alex
Last edited by alex on Thu Mar 31, 2011 4:52 pm, edited 1 time in total.