a question about the output of an MP4 calculation

[Bradley Welch]

All 

I am using Molpro 2025.4. I am attempting to perform an MP4 with no triples calculation. After the RHF calculation I get the following output as expected

PROGRAM * UMP4 (Unrestricted open-shell)     Authors: H.-J. Werner, 2001

Once it is done it outputs the following. Has MP4 been depreciated? QCISD is going to have some higher order terms that MP4(SDQ) wouldn't have. Do I need to use a UHF reference instead of RHF? 

  Reference energy                  -9674.797415244373
  UQCISD singles energy                -0.001941993262
  UQCISD pair energy                   -0.695680629015
  UQCISD correlation energy            -0.697622622276

 !RHF-UQCISD energy                 -9675.495037866649

[peterso...@gmail.com]

Brad,

this is an odd result/bug, but seems to occur from using HF rather than UHF orbitals.  Please specify UHF for the orbital part and it should work fine.

best wishes,

-Kirk

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