Role of Exact Exchange in Difference Projected Double-Hybrid Density Functional Theory for Treatment of Local, Charge Transfer, and Rydberg Excitations

Abstract

Difference approaches to the study of excited states have undergone a renaissance in recent years, with the development of a plethora of algorithms for locating self-consistent field approximations to excited states. Density functional theory is likely to offer the best balance of cost and accuracy for difference approaches, and yet there has been little investigation of how the parametrization of density functional approximations affects performance. In this work, we aim to explore the role of the global Hartree–Fock exchange parameter in tuning accuracy of different excitation types within the framework of the recently introduced difference projected double-hybrid density functional theory approach and contrast the performance with conventional time-dependent double-hybrid density functional theory. Difference projected double-hybrid density functional theory was demonstrated to give vertical excitation energies with average error and standard deviation with respect to multireference perturbation theory comparable to more expensive linear-response coupled cluster approaches (J. Chem. Phys.2020153074103). However, despite benchmarking of local excitations, there has been no investigation of the methods performance for charge transfer or Rydberg excitations. In this work we report a new benchmark of charge transfer, Rydberg, and local excited state vertical excitation energies and examine how the exact Hartree–Fock exchange affects the benchmark performance to provide a deeper understanding of how projection and nonlocal correlation balance differing sources of error in the ground and excited states.

Linear Scaling Calculations of Excitation Energies with Active-Space Particle–Particle Random-Phase Approximation

“…Time-dependent density functional theory − (TDDFT) ranks among the most used approach for finite systems because of the good compromise between the accuracy and the computational cost. TDDFT with commonly used density functional approximations (DFAs) has been widely applied to predict the excitation energies of different systems including molecules, liquids, and solids. − However, it is well known that TDDFT with conventional DFAs provides an incorrect long-range behavior. , Consequently, TDDFT fails to describe Rydberg and charge-transfer (CT) excitations. , Efforts including using range-separated functionals − and tuning the amount of the Hartree–Fock (HF) exchange in DFAs − have been made to address this issue. In addition, the accuracy of TDDFT largely depends on the exchange–correlation (XC) kernel .…”

Highly Sensitive and Selective Defect WS2 Chemical Sensor for Detecting HCHO Toxic Gases

“…By utilizing computed differences in charge density difference (CDD) [30] and charge transfer (B) [31], we can analyze the transfer of charges between the adsorption systems. This formula can be expressed as follows:…”