| 10:14:01 AM PDT - Mon, Sep 23rd 2013 |
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s^2 and UHF v ROHF energies
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Hi Edo,
Thanks for the suggestion. I have looked at the SCFs both UHF and ROHF and their associated S^2 values they are all correct and reproducible in other quantum chemistry packages:
i.e.
UHF(c1-c2) = + 7.5 kJ mol-1
ROHF(c1-c2) = +9.1 kJ mol-1
S^2(c1) = 1.16
S^2(c2) = 1.18
but
UCCSD(T)[c1-c2] = -1090.0 kJmol-1
ROCCSD(T)[c1-c2] = +9.7 kJ mol-1
The S^2 values are high but this is why I was careful making sure that I have the correct SCF solution (viz previous posts).
So why is the correlation energy so different for c2 doesn't make much sense to me? I thought it has something to do with the symmetry?
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