If you have problems during the execution of MRCC, please attach the output with an adequate description of your case as well as the followings:
  • the way mrcc was invoked
  • the way build.mrcc was invoked
  • the output of build.mrcc
  • compiler version (for example: ifort -V, gfortran -v)
  • blas/lapack versions
  • as well as gcc and glibc versions

This information really helps us during troubleshooting :)

Multi-reference CC active space setting for Sc2

  • ccu_tsai
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6 years 10 months ago - 6 years 10 months ago #367 by ccu_tsai
Dear All

I would like to do the MRCCSDTQ calculation for Sc2 molecule, but I found that the multiplicity is changed by the MRCC program. It may be the problem of the wrong active space for multiplicity 5. I know how to set the singlet state calculation, but how do I set the right active space for multiplicity 5 ? I would like to consider all 4s and 3d orbitals for each Sc. The following is my input file and the information for change of multiplicity.

My Input

# CCSD(T) calculation for triplet CH2 with cc-pVTZ basis, UHF orbitals
basis=m6-31G*
calc=CCSDTQ
mem=8000MB
mult=5
scfmaxit=130
#active=serialno
#19,20,21,22,23
nacto=5
nactv=1
#gopt=full
#freq=on
#symm=off

geom=xyz
2

SC 0.000000000000 0.000000000000 0.000000000000
SC 2.750000000000 0.000000000000 0.000000000000

The change of multiplicity in output

Allocation of 643.4 Mbytes of memory...
Number of spinorbitals: 100
Number of alpha electrons: 5
Number of beta electrons: 1
Spin multiplicity: 2
z-component of spin: 2.0
Spatial symmetry: 5
Convergence criterion: 1.0E-06
Construction of occupation graphs...
Number of 0 -fold excitations: 1
Number of 1 -fold excitations: 44
Number of 2 -fold excitations: 2761
Number of 3 -fold excitations: 78600
Number of 4 -fold excitations: 962852

Thanks a lot
Last edit: 6 years 10 months ago by ccu_tsai.

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  • kallay
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  • Mihaly Kallay
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6 years 10 months ago #368 by kallay
You should select the active space using the active keyword as
active=serialno
1-5

Best regards,
Mihaly Kallay
The following user(s) said Thank You: ccu_tsai

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  • ccu_tsai
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6 years 10 months ago - 6 years 10 months ago #369 by ccu_tsai
Thank for your suggestion, Dr. kallay. I understand how to set the active space now. :)
Last edit: 6 years 10 months ago by ccu_tsai.

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