# Re: Order of CASVB orbitals

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Posted by Takao Kobayashi on February 15, 2002 at 06:11:03:

In Reply to: Re: Order of CASVB orbitals posted by Thorstein Thorsteinsson on February 14, 2002 at 09:58:11:

: : I would like to change the order (or numbering) of the orbitals in the CASVB
: : wavefunction as I like, because I would like to know the weights of the preferable
: : structures in the CASVB wavefunction. I have tried to change the orders by using
: : Keywords "ORBPERM" and the order has somewhat changed. However I could not
: : have obtained the order which I expect. Please teach me how to change the order
: : of the orbitals in the CASVB wavefunction as I like.

: ORBPERM should do what you want. The idea is that it permutes orbitals and makes the
: corresponding changes to the structure coefficients. But note that the behaviour depends
: on where ORBPERM is put in the input. If you, for example, put it in the beginning, the
: (semi-random) starting-guess orbitals will be permuted. The converged orbitals may hence
: not be what you expect. If you converge the orbitals and *then* use ORBPERM, it should
: work the way you expect.

: Another potential source of confusion is that several ways of defining permutations
: exist. In casvb, ORBERM,3,-1,2,4 means [orbital 1 replaced by old orbital 3], [2 by -1],
: [3 by 2], and [4 by 4].

Following your advice, I tried but I have failed in obtaining the CASVB results as I like.
The CASVB part of my input file is as follows:

&casvb &end
COUPLE
RUMER
VBWEIGHTS
ALL
ORBPERM
2 1 9 4 3 8 6 5 10 7
PRINT
2 2 2 2 2 2 2
End of input

In this case, the order of CASVB orbitals changed just after initial guess and
the final results are not suitable. I would like the order of finally optimized CASVB
orbitals to change as I like and I would like to know the corresponding weight.

: : In addition, I have failed in taking the VB results from the VB information file
: : (VBWFN) using Keyword "START". Please show me how to read the VB results
: : from VBWFN.

: Something like
: START
: VB=JOBOLD
: should work. Can you give a little more details about how your input looks like?

Furthermore I have tried to take the CASVB results from a VBWFN file by using the
following input but I failed.

&casvb &end
START
VB=test.VbWfn
COUPLE
RUMER
VBWEIGHTS
ALL
ORBPERM
2 1 9 4 3 8 6 5 10 7
PRINT
2 2 2 2 2 2 2
End of input

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