# [molpro-user] MRCI with nosym option used not correct reference function from CAS

Peterson, Kirk kipeters at wsu.edu
Mon Jun 26 17:47:51 CEST 2017

```Dear David,

in your last mrci, please increase the pspace, i.e.,   pspace,1

best,

-Kirk

On Jun 26, 2017, at 2:40 AM, David Danovich <david.danovich at gmail.com<mailto:david.danovich at gmail.com>> wrote:

Hello,

I am trying to do freq calculation for F2(2+) molecule at MRCI level. For freq calculation I need to do CAS and MRCI without symmetry. As a first step, I have done CAS and MRCI with symmetry and got correct energies. Then I continue with nosym. For CAS I got the same energy as in the case with symmetry but for MRCI not.  For MRCI (nosym) calculation, program uses not correct reference energy and produces not correct total energy of MRCI. I was trying to use many option but without success.

Here is an input

***,F2(2+)
memory,350,m
gprint,orbital,civector;
gthresh,energy=1.d-10
r  = 1.6099 ang;
geometry={F1;                                                                   !z-matrix geometry input
F2,F1,r;
}

basis=aug-cc-pVTZ

{hf;accu,16;
wf,16,4,2}

{multi;
maxit,39;
wf,16,4,2;
orbital,2140.2}

{mrci;
orbit,2140.2;
wf,16,4,2}

symmetry,nosym

{hf;accu,16;
wf,16,1,2}

{multi;
start,2140.2;
maxit,39;
wf,16,1,2;
orbital,2240.2}

{mrci;
orbit,2240.2;
wf,16,1,2}

{frequencies;
symm,no}

Because output is too large I just put here part of it.

Here is energy  from symmetric CASSCF

Results for state 1.4
=====================

!MCSCF STATE 1.4 Energy             -197.330948763044

Here is results from non symmetric CASSCF (Both symm and nosymm have the same energies)

Results for state 1.1
=====================

!MCSCF STATE 1.1 Energy             -197.330948763044

Here is reference wavefunction from symmetric MRCI (it is the same as CASSCF)

Reference wavefunction optimized for reference space (refopt=1)

State     Reference Energy
1        -197.33094876

and here is energy

!MRCI STATE 1.4 Energy              -197.671580012360

Here is reference wavefunction from nonsymmetric MRCI (it is different from CASSCF)

Reference wavefunction optimized for reference space (refopt=1)

State     Reference Energy
1        -197.31016250

and the total energy is different from symmetric calculations

!MRCI STATE 1.1 Energy              -197.646905059678

What I am doing wrong in nosym MRCI calculation and what I need to do in order to get the right energy with nosym MRCI?

Thank you  David

--
<image003.jpg>Dr. David Danovich
The Lise Meitner Minerva Center for Computational Quantum Chemistry, Institute of Chemistry, The Hebrew University of Jerusalem,  Edmond J. Safra Campus - Givat Ram, 9190401 Jerusalem, Israel
http://yfaat.ch.huji.ac.il/david.html<https://urldefense.proofpoint.com/v2/url?u=http-3A__yfaat.ch.huji.ac.il_david.html&d=DwMFaQ&c=C3yme8gMkxg_ihJNXS06ZyWk4EJm8LdrrvxQb-Je7sw&r=mqaXWsZ0ghQR-pXvPLjY_g&m=1LhpxBjbE2AvLyNiO7J15nKuwn8Kh547OUP1l8O9XkY&s=2IpwVpfvIPV8Gz2d7DAUJAJ4dvrTjH5KaXLb_GO4w4c&e=>, e-mail: david.danovich at mail.huji.ac.il<mailto:david.danovich at huji.ac.il>
FAX:(+972)-2-6584033, Phone:(+972)-2-6586934(w),  Mobile:(+972)-544-768669
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