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Restoring Size Consistency of Approximate Functionals Constructed from the Adiabatic Connection
Stefan Vuckovic1, Paola Gori-Giorgi1, Fabio Della Sala2,3
1Department of Theoretical Chemistry and Amsterdam Center for Multiscale Modeling, FEW , Vrije Universiteit , De Boelelaan 1083 , 1081HV Amsterdam , The Netherlands.
The Journal of Physical Chemistry Letters
|May 23, 2018
Summary
Researchers have fixed a key flaw in density functional theory (DFT) calculations. New methods restore size consistency in approximate exchange-correlation functionals, improving accuracy for molecular interaction energies without extra cost.
Area of Science:
- Quantum Chemistry
- Computational Materials Science
- Theoretical Physics
Background:
- Approximate exchange-correlation (XC) functionals in density functional theory (DFT) are developed using nonlinear modeling of the adiabatic connection (AC) integrand.
- These functionals offer advantages like being virtually parameter-free and satisfying exact properties.
- A significant drawback is their violation of the size-consistency condition, which is essential for accurate molecular interaction energy calculations.
Purpose of the Study:
- To address the violation of size consistency in AC-based XC functionals.
- To introduce a computationally inexpensive method for restoring size consistency.
- To enhance the accuracy of DFT calculations for molecular interaction energies.
Main Methods:
- Modeling the adiabatic connection (AC) integrand in a nonlinear fashion.
- Developing a simple approach to restore size consistency in AC-based functionals.
- Testing the modified functionals on a comprehensive set of benchmark molecular interaction energies.
Main Results:
- A straightforward method was identified to restore size consistency in AC-based XC functionals.
- The proposed method incurs no additional computational expense.
- Functionals employing interaction strength interpolation approximations demonstrated superior accuracy compared to second-order perturbation theory for molecular interaction energies.
Conclusions:
- Size consistency can be effectively restored in AC-based DFT functionals with a simple, cost-free modification.
- This improvement significantly enhances the reliability of DFT for calculating molecular interaction energies.
- Interaction strength interpolation approximations offer a more accurate alternative to traditional methods like second-order perturbation theory.
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