Hiya,
I'm getting some unusual results while computing the counterpoise correction for binding energies of a formic acid dimer. When including ghost atoms with the vdw 3 dispersion correction I get energies which are ~0.2 Hartrees lower than the same calculation without the ghost atoms! This is a much much larger difference than I expected. A similar computation with vdw 2 gives results that are much closer.
So I wonder if there is some issue with ghost atoms and the vdw 3 correction?
Attached is my input script if anyone cares to check it.
Thanks.
EDIT: forgot to mention this is version 6.3.
start 2hcoohII.vdwd3
geometry units angstroms print xyz autosym
C 0.13610421 1.91612312 0.00000000
H 0.20980015 3.01221077 0.00000000
O 1.13159962 1.19699064 0.00000000
O -1.12156508 1.51388537 0.00000000
H -1.16041424 0.51093133 0.00000000
bqC -0.13610421 -1.91612312 0.00000000
bqH -0.20980015 -3.01221077 0.00000000
bqO -1.13159962 -1.19699064 0.00000000
bqO 1.12156508 -1.51388537 0.00000000
bqH 1.16041424 -0.51093133 0.00000000
end
basis spherical
H library "DZVP (DFT Orbital)"
O library "DZVP (DFT Orbital)"
C library "DZVP (DFT Orbital)"
bqH library H "DZVP (DFT Orbital)"
bqO library O "DZVP (DFT Orbital)"
bqC library C "DZVP (DFT Orbital)"
end
dft
xc b3lyp
disp vdw 3
end
task dft
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