Molcas Forum

freshman1234

Member

Registered: 2017-02-23

Posts: 18

State-Averaged CASSCF calculations with different spin multiplicty

I want to do the State-Averaged (SA) CASSCF calculations with different spin multiplicity, I want to calculate two lowest singlet states and a lowest triplet state,how can I edit the input file ?

Ignacio

Administrator

From: Uppsala

Registered: 2015-11-03

Posts: 1,085

Re: State-Averaged CASSCF calculations with different spin multiplicty

You cannot have different multiplicities (or spatial symmetries, or number of electrons) in a single SA calculations. You have to do a separate SA calculation for each one.

nikolay

Member

From: Stuttgart

Registered: 2016-03-21

Posts: 54

Re: State-Averaged CASSCF calculations with different spin multiplicty

If you really want to have State-Averaged CASSCF with different spin multiplicity or symmetry, you can use Molcas-Columbus interface. For now only binaries of Columbus are provided, see http://molcas.org/Columbus/.

ctser

Member

Registered: 2021-04-11

Posts: 1

Re: State-Averaged CASSCF calculations with different spin multiplicty

Hi, could I confirm if it is still not possible to perform SA-CASSCF with different spin multiplicities for the most recent versions of OpenMolcas? Apologies for missing the historical precedence for this post.

Also, I'd like to know if this input file would essentially optimize the S1/T2 crossing by state-averaging two singlet states and two triplet states separately, and that they are not state-averaged together? Thank you!

&GATEWAY
Coord=10

C         -6.15060        1.57918        0.14634
C         -5.07992        2.57577       -0.04362
H         -7.12747        2.06812       -0.05376
H         -6.19632        1.20323        1.19351
H         -6.07076        0.73174       -0.57161
C         -3.89849        1.74700        0.26132
H         -3.90425        1.37343        1.31032
H         -2.98949        2.37665        0.15814
H         -3.77875        0.90295       -0.45507
O         -5.18165        4.25227       -0.49816
Basis=ANO-RCC-MB
Group=NoSym
Constraints
 a = Ediff
 Value
 a = 0.000
End of Constraints
>>> EXPORT MOLCAS_MAXITER=500
>> Do While
&SEWARD
>>> If (Iter = 1) <<<
&SCF
>>> EndIf <<<
&RASSCF
NActel = 6
RAS2 = 5
Spin=1
Charge=0
CIRoot = 2 2 1
RlxRoot = 2
&ALASKA
PNEW
>>COPY $WorkDir/$Project.RunFile $WorkDir/RUNFILE2
&RASSCF
Spin=3
NActel = 6
RAS2 = 5
Charge= 0
CIRoot = 2 2 1
RlxRoot=1
&ALASKA
PNEW
&SLAPAF
>>> EndDo

Ignacio

Administrator

From: Uppsala

Registered: 2015-11-03

Posts: 1,085

Re: State-Averaged CASSCF calculations with different spin multiplicty

Correct, no SA between different symmetries yet (and no current plans to change that, as far as I know).