MEMCHK ERROR durring third order response calculation

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rlt92
Posts: 4
Joined: 20 Nov 2018, 12:29
First name(s): Richard
Last name(s): Thurston
Affiliation: UC Berkeley
Country: United States

MEMCHK ERROR durring third order response calculation

Post by rlt92 » 24 Jun 2019, 20:07

I'm trying to do an MCSCF calculation using Dalton 2018.1 to compute 2nd order hyperpolarizabilities of nitrobenzene but when I run that calculation I'm running into a MEMCHK error that seams to occur during the response calculation phase. I've tried running dalton with different amounts of memory (default, 12G, and 16G) but the error still occurs.

Attached is the shell output and the dalton output file. Any advice on how to fix this issue?
Attachments
NB_dftopt_ground_static_gamma_dunning_2zeta.out
(175.06 KiB) Downloaded 4 times
NB_dftopt_ground_static_gamma_dunning_2zeta shell output memchk error.txt
(8.3 KiB) Downloaded 3 times

hjaaj
Posts: 313
Joined: 27 Jun 2013, 18:44
First name(s): Hans Jørgen
Middle name(s): Aagaard
Last name(s): Jensen
Affiliation: Universith of Southern Denmark
Country: Denmark

Re: MEMCHK ERROR durring third order response calculation

Post by hjaaj » 25 Jun 2019, 08:29

There seems to be a memory allocation error when running with CSFs for cubic response. I think it will work if you run with determinants, to do that add the following to your input:

Code: Select all

*OPTIMIZATION
.DETERMINANTS
*CI VECTOR
.PLUS COMBINATIONS
-- Hans Jørgen.

PS. Your active space is not balanced, as can be seen from e.g. natural orbital occupancy close to 2. I usually use MP2 natural orbital occupancies to guide the selection of active space.

rlt92
Posts: 4
Joined: 20 Nov 2018, 12:29
First name(s): Richard
Last name(s): Thurston
Affiliation: UC Berkeley
Country: United States

Re: MEMCHK ERROR durring third order response calculation

Post by rlt92 » 25 Jun 2019, 19:03

Thanks for the reply!I'll let you know how it goes after I get a chance to run the calculation.

I have one additional question about choosing balanced active spaces. I was under the impression that a balanced active space would have an equal number of occupied vs unoccupied orbitals. Why is this incorrect and are there situations where an unbalanced orbital occupation would be more correct? I would also appreciate any recommending reading related to this question.

hjaaj
Posts: 313
Joined: 27 Jun 2013, 18:44
First name(s): Hans Jørgen
Middle name(s): Aagaard
Last name(s): Jensen
Affiliation: Universith of Southern Denmark
Country: Denmark

Re: MEMCHK ERROR durring third order response calculation

Post by hjaaj » 25 Jun 2019, 21:28

An unbalanced active space will never be more correct when doing response calculations. In fact, you have 10 electrons in 9 orbitals, so there will always at least be one occupied orbital without a correlating orbital ...

Another issue for balanced space, when the molecule has symmetry the primary correlating orbital is not always in the same irrep as the occupied orbital. (Textbook example: for homonuclear diatomics pi_u is bonding while the correlating antibonding orbital has pi_g symmetry.) In your case the two last irreps are pi orbitals, and clearly an orbital in symmetry 3 is correlating one of the orbitals in symmetry 4.

An MP2 natural orbital analysis shows that you probably want "3 3" orbitals in the last two irreps instead of "2 2".
You can get an MP2 natural orbital analysis by replacing .MCSCF with

Code: Select all

.HF
.MP2
and you can start the MCSCF from MP2 orbitals, a much better start guess than Huckel orbitals, with:

Code: Select all

.HF
.MP2
.MCSCF

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