Molcas Forum

maheshg

Member

Registered: 2018-09-25

Posts: 9

Alter orbitals while optimizing Singlet-Triplet crossing with CASSCF

Dear MOLCAS Developers and Users,

I recently started using OpenMolcas. I am trying to locate a singlet-triplet (S1/T2) crossing point in a system having 29 atoms using CASSCF method.

First, I ran a SCF calculation and visualized the corresponding MOs. This suggest that two particular MOs of SCF calculation (53 and 54; see below for copied input)need to be altered to ensure that the active orbitals is for the CASSCF calculation is correct.

For this purpose, I have made the following input in which the orbitals are altered in the first iteration. It runs fine till the first iteration and quits by printing the following error in the log file. I also have copied the input of the calculation.

***** Part of the output from the log file****

 ###    Location: get_dArray                                                 ###
 ###                                                                         ###
 ###                                                                         ###
 ###    Data of wrong length: Slapaf Info 2                                  ###
 ###                                                                         ###
 ###                                                                         ###
 ###############################################################################
 ###############################################################################
--- Stop Module: slapaf at Tue Oct  2 19:56:13 2018 /rc=_RC_INTERNAL_ERROR_ ---

****Input****

>export MOLCAS_MOLDEN=ON
&GATEWAY
Coord=test.xyz
Basis=6-31G**
Group=Nosym
Constraints
a = Ediff
Value
a = 0.000
End of Constraints

>>> Do while

&SEWARD

>>> IF (ITER = 1) <<<
&SCF
&RASSCF
Lumorb
Nactel = 8 0 0
Inactive = 54
RAS2 = 7
Ciroot = 2 2 1
Alter = 1
1 54 55
 >>> ENDIF <<<

&RASSCF
Lumorb
Nactel = 8 0 0
Inactive = 54
RAS2 = 7
Ciroot = 2 2 1
&ALASKA
>>COPY $WorkDir/$Project.RunFile $WorkDir/RUNFILE2

&RASSCF
Lumorb
Spin = 3
Nactel = 8 0 0
Inactive = 54
RAS2 = 7
Ciroot = 2 2 1
&ALASKA
&SLAPAF

>>> EndDo

Any suggestion in this regard would be deeply appreciated.

Thank you

Mahesh

Ignacio

Administrator

From: Uppsala

Registered: 2015-11-03

Posts: 1,079

Re: Alter orbitals while optimizing Singlet-Triplet crossing with CASSCF

I don't think it has anything to do with altering orbitals, but rather with file bookkeeping. I cannot try your input because you provide no system definition, but this works for me:

&GATEWAY
  Coord= 8

    C  1.878940  0.124540 -0.006680
    C  0.615900 -0.407680  0.011410
    C -0.555830  0.389670  0.010420
    O -1.755660 -0.097940 -0.007150
    H  2.223170  0.778990  0.774360
    H  2.573770 -0.086690 -0.796700
    H -0.467390  1.463440 -0.020470
    H  0.469610 -1.473830 -0.003700
  Basis=6-31G**
  Group=NoSym
  Constraints
    a = EDiff
  Value 
    a = 0.0
  End of constraints

>>> COPY $Project.RunFile $Project.Singlet.RunFile
>>> COPY $Project.RunFile $Project.Triplet.RunFile

>>> DoWhile

  >>> EXPORT SubProject=.Singlet
  &SEWARD
  >>> If (Iter = 1)
  &SCF
  &RASSCF
    Alter  = 1 ; 1 13 14
    Charge = 0
    NActEl = 2
    RAS2   = 4
    CIRoot = 2 2 1
  >>> EndIf

  &RASSCF
    Charge = 0
    NActEl = 2
    RAS2   = 4
    CIRoot = 2 2 1
  &ALASKA

  >>> EXPORT SubProject=.Triplet
  &SEWARD
  &RASSCF
    Spin   = 3
    Charge = 0
    NActEl = 2
    RAS2   = 4
    CIRoot = 2 2 1
  &ALASKA

  >>> COPY $Project.Singlet.RunFile $Project.RunFile2
  >>> COPY $Project.Triplet.RunFile $Project.RunFile
  >>> EXPORT SubProject=
  &SLAPAF
  >>> COPY $Project.RunFile2 $Project.Singlet.RunFile
  >>> COPY $Project.RunFile  $Project.Triplet.RunFile

>>> EndDo

It's basically adapted from test/additional/836.input

By the way, note that as it is written it will try to compute the crossing between the second singlet and triplet. If you want the lowest ones you'll have to add RlxRoot.

maheshg

Member

Registered: 2018-09-25

Posts: 9

Re: Alter orbitals while optimizing Singlet-Triplet crossing with CASSCF

Dear Ignacio,

Thank you very much for quick and helpful reply. The input works for me too.

I am having difficulties in understanding the input file, particularly the usage and necessity of "COPY" command.

Will you please elaborate on them?

Mean while, I will also try to understand them by going through the corresponding log file.

Thanks
Mahesh

Ignacio

Administrator

From: Uppsala

Registered: 2015-11-03

Posts: 1,079

Re: Alter orbitals while optimizing Singlet-Triplet crossing with CASSCF

Many of the files generated by molcas (orbitals, runfile, etc.) are called $Project$SubProject.*. By default SubProject is empty, so that is the same as $Project.*, but here we want to keep track of two different kinds of calculations (singlet and triplet), so we set SubProject accordingly. However, the runfile is created by GATEWAY, so we need to copy it to the two subprojects, otherwise the following calculations will not find it. Similarly, SLAPAF is run with SubProject="", so we need to (a) copy the subproject files as RunFile and RunFile2, and (b) copy back the files to the subprojects after SLAPAF has modified them (with, for instance, the new geometry).