Molcas Forum

brncat

Member

Registered: 2023-02-22

Posts: 2

ERROR: Number of (X)MULT states must be > 1.

Hello,

I notice that in the latest version of OpenMolcas (version: 23.02 tag: 3-g047e1685b) if I try to run CASPT2 for just one root for which I computed several states from CASSCF.

 &RASSCF &END
 EXPERT
 LUMORB
 Symmetry
 4
 Spin
 1
 nActEl
 14 1 0
 Inactive
 0 0 0 0
 Ras1
 2 0 0 0
 Ras2
 4 2 0 2
 Ras3
 0 0 0 0
 CIRO
 6 6 1
 End of input

&CASPT2
MAXITER
160
MULTistate = 1 1
IMAG
0.25
End of input

Then I get the following error message

 ###############################################################################
 ###############################################################################
 ###                                                                         ###
 ###                                                                         ###
 ###    ERROR: Number of (X)MULT states must be > 1.                         ###
 ###                                                                         ###
 ###                                                                         ###
 ###############################################################################
 ###############################################################################
 Last line read from input: 1 1 
--- Stop Module: caspt2 at Wed Feb 22 12:16:12 2023 /rc=_RC_INPUT_ERROR_ ---
*** files: xmldump

Is there another way, not documented, to compute single state CASPT2?

Best,
Bruno

vkj

Member

Registered: 2019-04-10

Posts: 27

Re: ERROR: Number of (X)MULT states must be > 1.

For Single-State CASPT2, you should add NOMULT keyword

stefabat

Member

Registered: 2019-12-02

Posts: 12

Re: ERROR: Number of (X)MULT states must be > 1.

Some internal behavior was changed to make the logic of the gradients work, and apparently I broke that way to specify single-state calculations (which is the way documented).
If NOMULT does not work either, try `LROOT = k` where k is the state number you are interested in. That should still work (albeit undocumented).
I will try to fix it and update the documentation as soon as possible.

Cheers,
Stefano

brncat

Member

Registered: 2023-02-22

Posts: 2

Re: ERROR: Number of (X)MULT states must be > 1.

Thank you Stefano!

Bruno