NWChem Frequently Asked Questions

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# NWChem FAQ ## MP2 Properties How do I calculate MP2 properties? My high symmetry MP2 calculation is taking longer that it should. Why is this? How do I calculate MP2 properties? The default molecular orbital file $file_prefix$.movecs is used unless a VECTORS subdirective is provided in the PROPERTY directive. It is therefore necessary to include a VECTORS directive if the MO vectors to be analyzed are not coming from the default file, e.g., if they have been previously redirected, or if MP2 natural orbitals (file extension ".mp2nos") are being anaylzed. So, to calculate MP2 properties, a PROPERTY block directive similar to the one in the following example would be appropriate:
          start h2o
          title; Water MP2 properties example

          geometry
            O 0  0     0
            H 0  1.430 1.107
            H 0 -1.430 1.107
          end

          basis
            H library sto-3g
            O library sto-3g
          end

          task mp2

          property
            octupole
            efield
            vectors h2o.mp2nos
          end

          task property
My high symmetry MP2 calculation is taking longer that it should. Why is this? Currently MP2 can only use Abelian point groups and does not have descent of symmetry implemented (meaning that it does not know how to use a proper Abelian point group instead of an input non-Abelian group). The user must define the proper Abelian point group, orient the molecule into this point group, and then run the MP2. NWChem | Capabilities | Platforms | Download | User's Manual | Programmer's Manual | Release Notes | FAQ Known Bugs | Support | Tutorial | Contributors | Benchmarks | Search | Mol Sci. Soft. Group | Citation Contact: NWChem Support Updated: February 22, 2005