Natural transition orbitals for complex two‐component excited state calculations

Abstract

While the natural transition orbital (NTO) method has allowed electronic excitations from time-dependent Hartree-Fock and density functional theory to be viewed in a traditional orbital picture, the extension to multicomponent molecular orbitals such as those used in relativistic two-component methods or generalized Hartree-Fock (GHF) or generalized Kohn-Sham (GKS) is less straightforward due to mixing of spincomponents and the inherent inclusion of spin-flip transitions in time-dependent GHF/GKS. An extension of single-component NTOs to the two-component framework is presented, in addition to a brief discussion of the practical aspects of visualizing two-component complex orbitals. Unlike the single-component analog, the method explicitly describes the spin and frequently obtains solutions with several significant orbital pairs. The method is presented using calculations on a mercury atom and a CrO 2 Cl 2 complex. K E Y W O R D S generalized Hartree-Fock, generalized Kohn-Sham, natural transition orbitals, relativistic methods, TDDFT, two-component electronic structure method

Target-Based Virtual Screening and LC/MS-Guided Isolation Procedure for Identifying Phloroglucinol-Terpenoid Inhibitors of SARS-CoV-2

“…The n → π* electronic transitions from S0 of the acylphloroglucinol moiety to S3 of the olefin group ( Figure 3 C) afforded a rotatory strength Δε = +0.8 at 304 nm, which was in agreement with the weak positive CEs Δε = +1.5 in the experimental ECD spectrum. 21 The other positive rotatory strength at electronic transitions between 304 and 350 nm was dominated by other π → π* characters of the acylphloroglucinol group (>90% contributions), which was consistent with the experimental positive CEs in the ECD spectrum. The negative rotatory band (Δε = −3.8) at 210 nm was in accordance with the experimental negative CE Δε = −2.8 in the ECD spectrum.…”

Spin–Orbit Natural Transition Orbitals and Spin-Forbidden Transitions

“…Therefore, the SO-NTOs are complex, but they do not have two components. The complex-valued SO-NTOs were plotted using the color wheel method proposed by Al-Saadon et al Kasper and Li also explored this plotting scheme for two-component complex orbitals. Here, at each point on a three-dimensional (3D) mesh grid, the angle θ of the complex phase exp­( i θ) of a complex-valued NTO is evaluated.…”

“…The methods include linear response time-dependent density functional theory (TDDFT), complete/restricted/generalized active space self-consistent field (RASSCF, CASSCF, GASSCF), − CI, , and equation-of-motion coupled-cluster (EOM-CC) . Kasper and Li recently extended the concept of NTOs in a TDDFT context to a two-component relativistic framework and visualized the complex-valued two-component NTOs.…”

Global Elucidation of Self-Consistent Field Solution Space Using Basin Hopping

“…The lowest RG solution (Figure 4 † ) describes the 1 B 2u wavefunction and is obtained from the unstable RU 1 B 2u solution by allowing the β spins (shown pointing down in Figure 4, although in nonrelativistic studies, the absolute spin Although interpretation of RG solutions in terms of (RR) orbitals is complicated due to mixing of spin components, 47 the RG solutions appear to be approximations of the other π → π* electronic states ( 1 B 1u and 1 E 1u ). Similar behavior is observed in the set of CU solutions where the real and imaginary components contain different π → π* transitions.…”

“…Three other RG solutions at 5.70, 5.88, and 5.89 eV have qualitatively the same spin density but with noncollinear sites having reduced symmetry across the σ v plane. Although interpretation of RG solutions in terms of (RR) orbitals is complicated due to mixing of spin components, the RG solutions appear to be approximations of the other π → π* electronic states ( 1 B 1 u and 1 E 1 u ). Similar behavior is observed in the set of CU solutions where the real and imaginary components contain different π → π* transitions.…”