Does anyone know
how Gaussian calculates deltaG of solvation? This was in G98 and was
automatic. In G03 one had to add SCFVAC in the scrf(CPCM,read) read list
to get the delta G result. I have several questions about the methods
used. I presume that during the SCRF calculation the program has to have a
separate SCF calculation on the input molecule in the gas phase, along
with a frequency calculation to know the free energy of the gas phase
structure. Is this correct? If so, are the ZPE and free energy
correction terms multiplied by a scale factor (0.92 for example?). Also to
do solvation energy calculations one need to convert the gas phase reference
state from 1 atmos. to 1 M. Does the program report this corrected delta G
value? My reason for asking
is that I have done these actual calculations separately with energy/frequency
calculations on the neutral and anion, and I get slightly difference answers
from those answers using SCFVAC, and I need to know why this
is? Regards, Dave
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