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Problem in running CCSDT(Q)

prasenjitseal
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4 years 7 months ago #886 by prasenjitseal

Problem in running CCSDT(Q) was created by prasenjitseal

Hi,

I am running one CCSDT(Q) calculations for a 14 atomic system and it came out with the following error. Could you please help me in solving this?

Here are part of the output file

Executing xmrcc...

**********************************************************************
CC(3)(4) calculation

Allocation of****** Mbytes of memory...
Number of spinorbitals: 236
Number of alpha electrons: 19
Number of beta electrons: 18
Spin multiplicity: 2
z-component of spin: 0.5
Spatial symmetry: 1
Convergence criterion: 1.0E-06
Construction of occupation graphs...
Number of 0 -fold excitations: 1
Number of 1 -fold excitations: 3681
Number of 2 -fold excitations: 4972671
Number of 3 -fold excitations: 3201647031
Total number of configurations: 3206623384
Calculation of coupling coefficients...
Length of intermediate file (Mbytes): 32978.1

======================================================================

Spin case 1 Alpha: 0 Beta: 4
Number of excitations: 11998948500

Fatal error in exec xmrcc.
Program will stop.

************************ 2020-04-16 10:37:23 *************************
Error at the termination of mrcc.
**********************************************************************

I ran similar calculations with 12 atoms and 25 valence electrons (13 alpha, 12 beta) and it terminates normally. Then where lies the issue here. Is it some sort of MEMORY issues. I used 360 GB of memory.

Thanks and best regards,
Prasenjit

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kallay
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Mihaly Kallay

4 years 7 months ago #887 by kallay

Replied by kallay on topic Problem in running CCSDT(Q)

Dear Prasenjit,
I do not think that a CCSDT(Q) calculation is feasible with so many electrons. I would use MP2 natural orbitals, see the description of keyword ovirt and J. Chem. Phys. 134, 124111 (2011).

Best regards,
Mihaly Kallay

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prasenjitseal
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4 years 7 months ago #888 by prasenjitseal

Replied by prasenjitseal on topic Problem in running CCSDT(Q)

Hi Mihaly,

Thanks for the info. Just wondering are any other Q variants of CC feasible with that much electrons.

Best regards,
Prasenjit

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kallay
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Mihaly Kallay

4 years 7 months ago #889 by kallay

Replied by kallay on topic Problem in running CCSDT(Q)

Unfortunately not, CCSDT(Q) is the least expensive one.

Best regards,
Mihaly Kallay

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prasenjitseal
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4 years 7 months ago #890 by prasenjitseal

Replied by prasenjitseal on topic Problem in running CCSDT(Q)

Thanks for the info. So, is it possible to increase the core electrons and reduce the valence electrons in MRCC. I mean are there any KEYWORDS for that?

Best,
Prasenjit

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kallay
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Mihaly Kallay

4 years 7 months ago #891 by kallay

Replied by kallay on topic Problem in running CCSDT(Q)

Please see keyword "core".

Best regards,
Mihaly Kallay

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Problem in running CCSDT(Q)

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