Correlation energy functional and potential from time-dependent exact-exchange theory

Area of Science:

• Quantum Chemistry
• Computational Physics
• Materials Science

Background:

• Density Functional Theory (DFT) is a powerful quantum mechanical modeling method.
• The exact-exchange (EXX) approximation is crucial for improving DFT accuracy.
• Accurate calculation of correlation energy is essential for predicting material properties.

Purpose of the Study:

• To introduce a novel functional for correlation energy within the time-dependent DFT framework.
• To assess the accuracy of this new functional for atomic systems.
• To simplify computational methods while maintaining high accuracy.

Main Methods:

• Utilized the exact-exchange (EXX) approximation within time-dependent DFT.
• Calculated correlation energies for various atomic species.
• Approximated the EXX kernel by its static value to simplify computations.
• Derived the correlation potential via functional differentiation.

Main Results:

• The new functional demonstrated excellent agreement with sophisticated methods for atomic correlation energies.
• Approximating the EXX kernel showed minimal loss of accuracy.
• The derived correlation potential proved remarkably accurate across all studied atoms.
• Calculated ionization potentials, polarizabilities, and van der Waals coefficients closely matched experimental values.

Conclusions:

• The developed functional offers a computationally efficient and accurate approach for correlation energy calculations.
• The simplified EXX approximation is viable for practical applications.
• The derived correlation potential shows significant promise for predicting atomic and molecular properties.