Probing Molecular Chirality of Ground and Electronically Excited States in the UV–vis and X-ray Regimes: An EOM-CCSD Study

Abstract

We present several strategies for computing electronic circular dichroism (CD) spectra across different frequency ranges at the equation-of-motion coupled-cluster singles and doubles level of theory. CD spectra of both ground and electronically excited states are discussed. For selected cases, the approach is compared with coupled-cluster linear response results as well as time-dependent density functional theory. The extension of the theory to include the effect of spin−orbit coupling is presented and illustrated by calculations of X-ray CD spectra at the L-edge.

Molecular Chirality and Its Monitoring by Ultrafast X-ray Pulses

“…The available methods include multi-configurational self-consistent field (MCSCF) approaches such as RASSCF (Restricted Active Space Self Consistent Field), 224,225 density density functional theory such as TDDFT (Time-Dependent Density Function Theory), [226][227][228][229] pertubation theories including the ADC (Algebraic-Diagrammatic Construction methods) schemes and coupled pair theories such as EOM-CC (Equationof-Motion Coupled-Cluster). [230][231][232][233][234] Numerical strategies for optical chiral signals have been extensively discussed by Crawford et al 235 while the computation of core-excited states have recently been reviewed by Norman et al 236 Some specific care must be used to calculate higher order multipoles with acceptable precision. In any ab initio calculation involving various multipoles, one must keep in mind that only the first non-vanishing transition multipole, typically the electric dipole, is origin invariant.…”

“…These signals require the computation of core-excited states and their transition multipole moments. The available methods include multiconfigurational self-consistent field (MCSCF) approaches such as RASSCF (restricted active space self consistent field), , density functional theory such as TDDFT (time-dependent density function theory), − perturbation theories including the ADC (algebraic-diagrammatic construction methods) schemes, and coupled pair theories such as EOM-CC (equation-of-motion coupled-cluster). − Numerical strategies for optical chiral signals have been extensively discussed by Crawford et al while the computation of core-excited states has recently been reviewed by Norman et al…”

Quantum self-consistent equation-of-motion method for computing molecular excitation energies, ionization potentials, and electron affinities on a quantum computer

“…A number of methods have been developed in this regard in the last few decades [24][25][26][27][28][29][30]. The equation-of-motion coupled-cluster (EOM-CC) [26] approach, originally developed by Stanton and Bartlett, is a popular example that is routinely used to calculate molecular excited-state properties such as excitation energies and transition dipole moments [31][32][33][34][35]. EOM-CC has also been extended to calculate energies required to add or remove electrons from the ground-state electronic configuration [36][37][38][39][40].…”

Cherry-Picking Resolvents: Recovering the Valence Contribution in X-ray Two-Photon Absorption within the Core–Valence-Separated Equation-of-Motion Coupled-Cluster Response Theory

“…Within the CC domain, the CVS scheme was pioneered by Coriani and Koch , for computing core-excitation energies (and spectral intensities) as well as core-ionization energies. Since then, the CVS strategy has been used in several CC-RSP and EOM-CC frameworks, ,,, enabling the modeling of XAS, XPS, XCD, and XES spectra. ,− The theory was further extended to higher-order properties such as resonant inelastic X-ray scattering (RIXS) cross sections. − Similar to 2PA, RIXS is a two-photon process; RIXS moments are also formally given by sum-over-states (SOS) expressions within the EOM-CC expectation-value framework. In practical calculations, the SOS expressions are recast into closed-form expressions by using first-order response wave functions.…”