Robust and accurate hybrid random-phase-approximation methods.

Area of Science:

• * Quantum Chemistry
• * Computational Materials Science

Background:

• * Standard density functional theory (DFT) methods face challenges with accuracy for certain chemical properties.
• * Direct random phase approximation (dRPA) methods offer improvements but can suffer from convergence issues.
• * Hybrid functionals combine exact exchange with DFT, aiming for better accuracy.

Purpose of the Study:

• * Introduce a novel self-consistent hybrid dRPA method (sc-H[γ]dRPA) with improved accuracy and stability.
• * Evaluate the performance of sc-H[γ]dRPA and a related non-self-consistent method (dRPA@PBE[γ]) for chemical energy calculations.
• * Compare these new methods against existing dRPA and wavefunction-based approaches.

Main Methods:

• * Development of the sc-H[γ]dRPA method incorporating a fraction of nonlocal Hartree-Fock-like exchange.
• * Implementation of a non-self-consistent dRPA@PBE[γ] method using PBE0 hybrid functional orbitals.
• * Testing against established methods like PBE-based dRPA, MP2, and CCSD(T) for reaction, isomerization, and transition state energies.

Main Results:

• * sc-H[γ]dRPA converges well for systems with small eigenvalue gaps, unlike standard self-consistent dRPA.
• * sc-H[γ]dRPA and dRPA@PBE[γ] (with γ=1/3) provide significantly more accurate energies than PBE-based dRPA.
• * Both new methods outperform MP2 and CCSD(T) with better computational scaling.
• * sc-H[γ]dRPA yields qualitatively correct correlation potentials, a feat not achieved by standard DFT.

Conclusions:

• * The sc-H[γ]dRPA method presents a robust and accurate approach for electronic structure calculations.
• * The computationally efficient dRPA@PBE[γ] offers comparable accuracy for energy calculations.
• * These hybrid dRPA methods represent a significant advancement in computational chemistry, offering improved accuracy and stability.