[molpro-user] dissociating H2 molecule?

[Julius T. Su]

Hello,

  I had two questions -- (1) how can I make a UHF wavefunction corresponding to dissociating H2 and (2) what correlation methods would be accurate for this case?

  For (1), I can handle the triplet case without any problem, just by specifying the right symmetry orbitals to be open-shell.  However this doesn't work for the singlet case, either with or without symmetry.  Could someone show me how to do this?  (I know it's not an s^2 eigenfunction, but that should still be all right with molpro, right?) 

  For (2), is there a CCSD(T) method that starts from a UHF wavefunction?  Is it reasonable to expect an RHF based method to handle this case well?  CR-CCSD(T) in GAMESS handles H+H well, do the UCCSD(T) methods in molpro work similarly? 

Thanks,

Julius