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Interpair electron correlation by second-order perturbative corrections to PNOF5.

M Piris1

  • 1Kimika Fakultatea, Euskal Herriko Unibertsitatea (UPV/EHU), P.K. 1072, 20080 Donostia, Spain.

The Journal of Chemical Physics
|August 17, 2013
PubMed
Summary
This summary is machine-generated.

Piris natural orbital functional 5 (PNOF5) calculations were enhanced with second-order corrections (SC2-MCPT). This improved method accurately describes dispersion interactions and molecular dissociation, aligning well with experimental data.

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Area of Science:

  • Quantum chemistry
  • Computational physics
  • Theoretical chemistry

Background:

  • Piris natural orbital functional 5 (PNOF5) is a method for electronic structure calculations.
  • Second-order corrections are needed to improve the accuracy of approximate quantum chemical methods.

Purpose of the Study:

  • To derive and implement second-order corrections to PNOF5 using size-consistent second-order multiconfigurational perturbation theory (SC2-MCPT).
  • To propose a modified SC2-MCPT approach for improved description of dispersion interactions and molecular dissociation.

Main Methods:

  • Utilizing an antisymmetrized product of strongly orthogonal geminals for PNOF5.
  • Implementing SC2-MCPT with explicit expansion coefficients based on occupation numbers.
  • Developing a modified SC2-MCPT focusing on doubly excited determinants from different geminals.

Main Results:

  • The SC2-MCPT formulation provides accurate second-order corrections to PNOF5.
  • The modified SC2-MCPT successfully describes dispersion interactions in the helium dimer.
  • The method avoids curve breakdown in homolytic dissociations of FH, CO, and N2.

Conclusions:

  • The developed SC2-MCPT method offers significant improvements over standard PNOF5.
  • The formulation accurately predicts molecular properties, demonstrating its potential for computational chemistry applications.