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A time-dependent formulation of multi-reference perturbation theory.

Alexander Yu Sokolov1, Garnet Kin-Lic Chan1

  • 1Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA.

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|February 15, 2016
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Summary
This summary is machine-generated.

We introduce a new time-dependent formulation for perturbation theory (t-NEVPT2) applicable to multi-reference situations. This method offers a computationally efficient way to calculate electronic wavefunctions and energies for molecules.

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Area of Science:

  • Quantum Chemistry
  • Computational Chemistry
  • Theoretical Chemistry

Background:

  • Perturbation theory is crucial for understanding molecular electronic structure.
  • Multi-reference situations require advanced theoretical approaches.
  • Existing methods for n-electron valence perturbation theory can be computationally intensive.

Purpose of the Study:

  • To develop a time-dependent formulation of perturbation theory for multi-reference systems.
  • To implement and test the time-dependent n-electron valence second-order perturbation theory (t-NEVPT2) method.
  • To assess the computational efficiency and accuracy of t-NEVPT2.

Main Methods:

  • Formulation of time-dependent perturbation theory for interacting zeroth-order Hamiltonians.
  • Implementation of second-order n-electron valence perturbation theory in a time-dependent framework.
  • Application of the t-NEVPT2 method to calculate wavefunctions and energies.

Main Results:

  • The t-NEVPT2 method provides fully uncontracted wavefunctions and energies.
  • t-NEVPT2 exhibits lower computational scaling compared to traditional contracted methods.
  • The method avoids the need for high-order density matrix construction and metric diagonalization.
  • Successful application of t-NEVPT2 to water, nitrogen, carbon, and chromium molecules.

Conclusions:

  • The time-dependent n-electron valence second-order perturbation theory (t-NEVPT2) is a viable and efficient method for multi-reference electronic structure calculations.
  • t-NEVPT2 offers a computationally advantageous alternative to existing methods.
  • Further development and application of t-NEVPT2 are warranted for complex molecular systems.