PC GAMESS/Firefly-related discussion club

Learn how to ask questions correctly

Pasquale Morvillo
pasquale.morvillo@portici.enea.it

On Thu Nov 5 '09 2:06am, sanya wrote
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>>The manual states that $FORCE group is relevant only for RUNTYP=HESSIAN, OPTIMIZE and SADPOINT but the question was about RUNTYP=ENERGY....

>Previously, we discussed thermochemistry, so I thought the question was about energy for thermochemistry. Of course, the energy of, say, single point calculation (without vibrations taken into account) corresponds to 0 K. To put it more precisely, this energy corresponds to a certain point lying exactly on the PES, i.e., to no temperature. After taking into account vibrations (for example, with RUNTYP=HESSIAN), ZPE correction gives the energy at 0 K, and including any nonzero temperature (by default, 298.15 K) gives the corresponding thermochemically relevant value.