I run RI-MP2 calculation of cubane molecule (C8H8) in a different bases.
cc-pCVTZ, cc-pCVQZ looks good, but with cc-pCV5Z basis I have got unrelailable MP2 energy.
my input file is (molecular geometry is almost equilibrium):
title "cubane cc-pV5Z MP2-RI energy"
geometry
symmetry Oh
H 1.41063149 1.41063149 1.41063149
C 0.78371973 0.78371973 0.78371973
end
basis
H library cc-pV5Z
C library cc-pCV5Z
end
basis "ri-mp2 basis"
H library cc-pV5Z-ri
C library cc-pV5Z-ri
end
task rimp2
output energy is:
-------------------------------------------
SCF energy -307.507255162945
Correlation energy -4369.270156917300
Total MP2 energy -4676.777412080244
-------------------------------------------
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