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MP2 and RI-MP2

We recommend to use MP2 together with the RI technique: program rimp2 or ricc2. This is more efficient and supports the frozen core option in the gradient calculation.

The entry mp2 leads to a submenu which allows to set some keywords for MP2 and RI-MP2 calculations, e.g. defining frozen orbitals, maximum memory usage, or assign auxiliary basis sets for RI-MP2 calculations, etc. If you want to use ricc2, you have to use the entry cc2 and the submenu ricc2 in order to assign MP2 as wavefunction model. It covers all keywords required for rimp2 calculations, Mandatory for rimp2 runs is the specification of the auxiliary basis set using the menu entry cbas. (Alternatively, the rimp2prep tool can be used to set the keywords needed for rimp2 calculations.)

Conventional MP2 calculations with mpgrad require a number of additional settings for which it is recommended to invoke the interactive tool mp2prep. For geometry optimizations with jobex use nohup jobex -level mp2 -ri ...