[molpro-user] Retaining SB in SCF

[Eric Jon Sundstrom]

I am wondering if there is an easy way to retain unrestricted type
symmetry-breaking during the SCF procedure using Molpro. I have included
below an example for H2, where DIIS takes me back to the RHF solution even
though there a lower energy UHF solution.  In this case it would be easy to
generate the correct wavefunction but I need this for computing UHF
solutions of transition metal systems where it isn't possible to write down
the correct wavefunction.

Thank you,
EJS

***, H2-Example
memory,1500,M
NOSYM
geometry={
2

H 0 0 0
H 0 0 1.5
}
basis=sto-3g
NOENEST=yes
{rhf,maxdis=50,iptyp='DIIS',maxit=500,orbital=2100.2,accu=10,energy=1e-12}

{MERGE
ORBITAL,2100.2
MOVE,1.1,,1.1
ROT,1.1,2.1,30
SAVE,2100.2
}
NOENEST=yes
{uhf,maxdis=50,iptyp='DIIS',maxit=500,orbital=2100.2,accu=10,energy=1e-12}

-------------------------------------------------------------------
Dr. Eric Jon Sundstrom

Postdoctoral Researcher

Thomas F. Miller III Group
Division of Chemistry and Chemical Engineering
California Institute of Technology
ph: 765.491.5765
email: esundstr at gmail.com

On Tue, Sep 23, 2014 at 1:01 PM, Eric Jon Sundstrom <esundstr at gmail.com>
wrote:

> I am wondering if there is an easy way to retain unrestricted type
> symmetry-breaking during the SCF procedure using Molpro. I have included
> below an example for H2, where DIIS takes me back to the RHF solution even
> though there a lower energy UHF solution.  In this case it would be easy to
> generate the correct wavefunction but I need this for computing UHF
> solutions of transition metal systems where it isn't possible to write down
> the correct wavefunction.
>
> Thank you,
> EJS
>
> ***, H2-Example
> memory,1500,M
> NOSYM
> geometry={
> 2
>
> H 0 0 0
> H 0 0 1.5
> }
> basis=sto-3g
> NOENEST=yes
> {rhf,maxdis=50,iptyp='DIIS',maxit=500,orbital=2100.2,accu=10,energy=1e-12}
>
> {MERGE
> ORBITAL,2100.2
> MOVE,1.1,,1.1
> ROT,1.1,2.1,30
> SAVE,2100.2
> }
> NOENEST=yes
> {uhf,maxdis=50,iptyp='DIIS',maxit=500,orbital=2100.2,accu=10,energy=1e-12}
>
>
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