Author Topic: rimp2 energy comparison  (Read 2338 times)

jbaltrus

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rimp2 energy comparison
« on: February 06, 2013, 05:24:34 pm »
I should probably not do that, but it bothers me so I will. I calculated mp2 (ricc2 ) single point energy with def2-TZVP in TURBOMOLE and ORCA. RHF energies for both are almost identical..

ORCA  -18373.81677195 Eh
TURBOMOLE -18373.8167659600

Perfect!

However, after correlation (and freezing the same number of orbitals), result is very different, e.g.

ORCA: RI-MP2 CORRELATION ENERGY:    -20.005401695 Eh
TURBOMOLE: correlation energy                      :    -20.4917897873

What could be the culprit, I am tempted using lower energy TURBOMOLE value but not sure what might have went differently during correlation calculations. Again, the same number of orbitals was frozen

Jonas

christof.haettig

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Re: rimp2 energy comparison
« Reply #1 on: September 25, 2015, 02:47:35 pm »
This looks like a large molecule...
1.) check if both programs did indeed freeze the same core orbitals and that the correct core orbitals were picked.
2.) check that both programs did RI-MP2 calculations (e.g. check that TM did not do a CC2 calc.)
3.) check that you used both programs with the auxiliary basis sets.