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Computation of Atmospheric Concentrations of Molecular Clusters from ab initio Thermochemistry
Published on: April 8, 2020
Communication: explicitly-correlated second-order correction to the correlation energy in the random-phase
Anna-Sophia Hehn1, Wim Klopper
1Karlsruhe Institute of Technology, Institute of Physical Chemistry, Theoretical Chemistry Group, KIT Campus South, P.O. Box 6980, 76049 Karlsruhe, Germany.
The Journal of Chemical Physics
|May 17, 2013
Summary
The random-phase approximation (RPA) for correlation energy shows slow basis-set convergence, similar to wavefunction methods. However, using explicitly correlated two-electron functions accelerates this convergence, matching wavefunction theory approaches.
Area of Science:
- Quantum Chemistry
- Computational Physics
- Materials Science
Background:
- The random-phase approximation (RPA) is a method for calculating correlation energy in electronic structure theory.
- Wavefunction theory methods like coupled-cluster and many-body perturbation theory also face challenges with basis-set convergence.
- Slow basis-set convergence necessitates larger basis sets, increasing computational cost.
Purpose of the Study:
- To investigate the basis-set convergence of correlation energies calculated using the random-phase approximation.
- To explore methods for accelerating the slow basis-set convergence observed in RPA calculations.
- To compare the convergence behavior of RPA with established wavefunction theory methods.
Main Methods:
- Density-functional theory (DFT) framework.
- Random-phase approximation (RPA) for correlation energy.
- Explicitly correlated two-electron basis functions (dependent on interelectronic distances).
- Comparison with coupled-cluster (CC) and many-body perturbation theory (MBPT) methods.
Main Results:
- Correlation energies obtained from RPA exhibit slow basis-set convergence, comparable to wavefunction theory.
- The slow convergence of RPA correlation energies can be effectively accelerated.
- Acceleration is achieved by employing explicitly correlated two-electron basis functions, similar to techniques used in wavefunction theory.
Conclusions:
- Explicitly correlated basis functions offer a viable strategy to accelerate the slow basis-set convergence of RPA correlation energies.
- This acceleration makes RPA a more computationally efficient method for obtaining accurate correlation energies.
- The findings provide a pathway to enhance the applicability of RPA in electronic structure calculations.
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