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The well-tempered auxiliary-field Monte Carlo
1Department of Physical Chemistry and the Lise Meitner Minerva-Center for Quantum Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
The Journal of Chemical Physics
|July 23, 2004
Summary
Well-tempered auxiliary-field Monte Carlo (AFMC) improves calculations of molecular energies by efficiently treating electron correlation. This enhanced method also provides low-lying excitation energies as a byproduct.
Area of Science:
- Quantum chemistry
- Computational physics
Background:
- Auxiliary-field Monte Carlo (AFMC) is a computational method for determining molecular ground-state and excited-state energies.
- AFMC accuracy depends on the inverse temperature parameter 'beta', efficiently capturing dynamical correlation but struggling with nondynamical correlation due to increasing statistical errors with 'beta'.
Purpose of the Study:
- To investigate a multi-determinant variant of AFMC.
- To enhance the efficiency and accuracy of AFMC for molecular property calculations.
- To explore the method's capability in calculating excitation energies.
Main Methods:
- Utilizing a multi-determinant variant of auxiliary-field Monte Carlo (AFMC).
- Tuning the method by balancing determinantal space size and the 'beta' parameter.
- Applying the well-tempered AFMC approach to molecular systems.
Main Results:
- The well-tempered AFMC demonstrates significantly improved efficiency compared to naive AFMC.
- The method effectively recovers both dynamical and nondynamical correlation energies.
- Low-lying excitation energies were obtained as a byproduct of the calculations.
Conclusions:
- The multi-determinant, well-tempered AFMC offers a more efficient and accurate approach for calculating molecular energies and properties.
- This enhanced AFMC method provides valuable insights into both ground-state and excited-state properties, including excitation energies.