Questions tagged [mrcc]

For questions about (or involving) the MRCC electronic structure software package.

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16
votes
3answers
186 views

How is “basis set projection” done?

I recently came across something called the basis set projection in Q-chem's manual. What it seems to do is to take the converged SCF in a smaller basis set, and then "projects" that onto a ...
8
votes
2answers
186 views

What are Pair Natural Orbitals?

Recently, I came across electron correlation methods that use local pair natural orbitals (LPNOs) or domain-based local pair natural orbitals (DLPNO), such as DLPNO-MP2, DLPNO-CCSD etc. The dynamic ...
10
votes
2answers
313 views

Analytic gradient for DLPNO-CCSD

Is there a formula for analytical gradients (for geometry optimization) for the DLPNO-CCSD method? I ask because I know that it is not implemented in ORCA. Maybe PNO-CCSD is implemented in MRCC or ...
8
votes
1answer
71 views

Interfacing MRCC with CFOUR for dynamic polarizability

I have asked this question on the MRCC forum but did not get an answer. I am trying to understand how to use CFOUR with the MRCC program for computing dynamic polarizability. To begin with, I am ...
16
votes
3answers
280 views

How to calculate homolytic bond dissociation energies?

An experimental colleague asked me how hard it would be to calculate homolytic bond-dissociation energies for different phosphonates which are involved in a Hydrophosphination. The compounds include ...
20
votes
3answers
224 views

What is the largest system that has been studied by the coupled cluster method?

This is parallel to the analogous question about the largest DFT calculation: What is the largest material that has been studied using density functional theory? I assume we allow high performance ...