[molpro-user] MS-CASPT2 for MOLPRO

Mitchell Ong mong2 at uiuc.edu
Mon Apr 9 21:03:52 BST 2007

Dear Molpro users,

I have a few questions about the MS-CASPT2 routine implemented in MOLPRO 2006.1.  

1.)  I would get in the output:

 Recalculated energy wrong
 Eigenvalue(2)=           -155.24783247539050
 D2(t).Heff.D2=           -155.24783247539030
 difference    =    0.1989519660E-12 
 The recalculated energy D2(t).Heff.D2will be stored in MSENERGY

If the energy stored in MSENERGY is incorrect, what would be the correct MS-CASPT2 energy?  

2.)  Also, what is the difference between the Heff-Brandow MS-CASPT2 energy and the Heff Sum Symmetrized MS-CASPT2 energies?  Which one can I trust more?  One of my coworkers is seeing that states can change order from one definition to the other and the energy gaps between states can also be different.

3.)  Do the transition dipole moments at the end of the rs2 calculation correspond to single state CASPT2 or MS-CASPT2 if a MS-CASPT2 calculation is performed?

4.)  Finally, I tried to do a MS-CASPT2 gradient calculation for one of the excited states.  The input for the MS-CASPT2 part is:

 state, 4

I specified the gradient for state 2, but what I see printed out in the output is:


It says it's calculating the gradient for state 1, but I ask for state 2.  Is this gradient for state 2 but mislabeled or is this gradient for state 1?

Any insight to these questions would be appreciated.  Thanks

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