arXiv subjects

Duy-Khoi Dang

Publications and source records attributed to Duy-Khoi Dang.

3 recordsLinked to original sources

arXiv2025

Numerical Integration of Slater Basis Functions Over Prolate Spheroidal Grids

Slater basis functions have desirable properties that can improve electronic structure simulations, but improved numerical integration methods are needed. This work builds upon the SlaterGPU library for evaluation of Hamiltonian matrix elements in the resolution-of-the-identity approximation. In particular, a Prolate Spheroidal grid will provide sufficient integral accuracy to employ larger basis sets (quadruple-zeta and greater) in practical computations involving polyatomics. To integrate 3-center Coulomb and nuclear attraction terms, an improved grid representation around the 3rd center is introduced. The RMSEs of the integral quantities are evaluated and compared to the previous numerical integration method used in SlaterGPU (Becke Partitioning), resulting in a ~3 order of magnitude reduction in the error for 2-center integral quantities. The procedure is generally applicable to polyatomic systems, GPU accelerated for high performance computing, and tested on self-consistent field and full configuration interaction wavefunctions. Results for a number of 3-atom models as well as propanediyl (C3H6) demonstrate the reliability of the new integration scheme.

physics.chem-ph↗

arXiv2025

Many-Body Basis Set Amelioration Method for Incremental Full Configuration Interaction

Incremental full configuration interaction (iFCI) is polynomial-cost approach to the FCI limit of electronic structure. This article introduces the many-body basis set amelioration (MBBSA) method, which is designed to allow iFCI to be applicable to larger atomic orbital basis sets. MBBSA uses a series of inexpensive iFCI calculations to approximate the correlation energy that would be found using a more expensive, highly accurate iFCI calculation. When compared to standard iFCI computations on smaller molecules in triple-zeta and larger basis sets, MBBSA provides approximations to total and relative energies within chemical accuracy. MBBSA yields cost savings of between 60 and 92% when compared to standard iFCI calculations, with larger systems having increased savings. Tests of MBBSA on two reactions that involve highly correlated systems, the automerization of cyclobutadiene and a Criegee intermediate reaction, show that MBBSA has practical utility for studying realistic chemistries.

physics.chem-ph↗

arXiv2023

Exchange Correlation Potentials from Full Configuration Interaction in a Slater Orbital Basis

Ryabinkin-Kohut-Staroverov (RKS) theory builds a bridge between wave function theory and density functional theory by using quantities from the former to produce accurate exchange-correlation potentials needed by the latter. In this work, the RKS method is developed and tested alongside Slater atomic orbital basis functions for the first time. To evaluate this approach, Full Configuration Interaction computations in the Slater orbitals are employed to give quality input to RKS method, allowing full correlation to be present along with correct nuclei cusps and asymptotic decay of the wavefunction. The RKS method will be shown to be an efficient algorithm to arrive at exchange correlation potentials without unphysical artifacts in moderately-sized basis sets. Furthermore, enforcement of the nuclear cusp conditions will be shown to be vital for the success of the Slater-basis RKS method. Examples of weakly and strongly correlated molecular systems will demonstrate the main features of Slater RKS.

physics.chem-ph↗