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Re: my question was not clear, i mean...

Alex Granovsky


this is impossible to do without computing Hessian and performing
vibrational analysis first, and so unfortunately the answer on your
questions is negative - you cannot correct frequencies and
thermodynamic functions, you can only correct geometry.

Alex Granovsky

On Tue Jun 28 '11 2:25pm, Eldar Mamin wrote
>>By what method can i estimate frequences if i have got mrmp2 geometry and energy (by technique i described, irc_mcscf+energy_mrmp2) for Eelect and Evib, Svib, Hvib would be calculated approximately on the same level of theory.

>On Fri Jun 24 '11 6:24pm, Alex Granovsky wrote
>>Dear Eldar,
>>Indeed, both mrmp2 and qdpt gradients and hessians are not yet available.

>>Alex Granovsky

>>On Sat Jun 18 '11 7:10pm, Eldar Mamin wrote
>>>Dear FireFly users

>>>I have performed IRC-calculation(MCSCF) for some system and then, mrmp2 energies for these irc points. So a new geometry of saddle point has been obtained. I need hessian to compute, and then thermodynamic functions. In what method should i calculate hessian and for what geometry (mcscf or mrmp2 and other). As far as i now mrmp2 hessian is yet unavaliable for mrmp2.

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