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Problem running XMCQDPT2 calculation with large (16e,16o) active space
I have been using Firefly recently to run CASSCF and XMCQDPT2 calculations on a medium-sized organic photochromic system. This system requires a large active space: (14e,14o) to study its absorption properties and (16e,16o) to study its photoswitching mechanism. While I have been able to run XMCQDPT2 with a (14e,14o) active space, I am not able to run a similar job with a (16e,16o) active space. I cannot circumvent the memory limit in mwords. I get the following error message in MQCACI: ERROR: MEMORY REQUEST EXCEEDS MAXIMUM. 729888763 WORDS REQUIRED 460000000 AVAILABLE.
Maybe someone can tell me if this calculation is possible or not. I have enclosed an input file in which the CASSCF(16,16) part is skipped as the CASSCF orbitals have been saved in a previous job.
I would be extremely grateful if I can get some assistance with this issue as the whole series of calculations I am planning to perform require this large (16e,16o) active space.
I am using the 8.2.0 version.
Many thanks in advance!
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[ boggio_xmcqd16pt2_vtz_input.tar.gz ] Complet input file and external basis set file
Wed Jan 24 '18 6:53pm
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