Enhancing the electron pair approximation with measurements for the variational quantum eigensolver

A system for enhancing accuracy of electron pair approximation using non-bosonic perturbation (PT2) correction, comprising:

• a computing device, comprising:
• a processor;
• a memory;
• and
• a graphical user interface,
• wherein:
• the processor is configured to generate a unitary pair coupled cluster double (upCCD) Ansatz to determine geometry coordinates of a molecule,
• the graphical user interface is configured to receive, as input, the geometry coordinates of the molecule, and
• the processor is further configured to:
• perform orbital optimization to generate an orbital optimization upCCD (oo-upCCD) comprising an energy calculation;
• and
• perform energy correction on the energy calculation of the oo-upCCD based on a second order perturbation theory (PT2), generating a PT2 correction energy value of the molecule.

A system for enhancing accuracy of electron pair approximation using non-bosonic perturbation (PT2) correction, comprising:

• a computing device, comprising:
• a processor;
• a memory;
• and
• a graphical user interface,
• wherein the memory is configured to store programming instructions that, when executed by the processor, are configured to cause the processor to:
• generate a unitary pair coupled cluster double (upCCD) Ansatz to determine geometry coordinates of a molecule;
• enable the graphical user interface to receive, as input, the geometry coordinates of the molecule;
• perform orbital optimization to generate an orbital optimization upCCD (oo-upCCD) comprising an energy calculation;
• and
• perform energy correction on the energy calculation of the oo-upCCD based on a second order perturbation theory (PT2), generating a PT2 correction energy value of the molecule.