We present the theory and implementation of a fully variational wave function–density functional (DFT) hybrid model, which is applicable to many cases strong correlation. denote this model as multiconfigurational self-consistent on-top pair-density (MC-srPDFT) model. have previously shown how short-range DFT (MC-srDFT) can describe any spin symmetry also state-specific calculations on excited states [Hedegård et al., J. Chem. Phys. 148(21), 214103 (2018)]. However, srDFT part MC-srDFT has...

Core-electron excitations in solvated systems, influenced by solvent geometry and hydrogen bonding, make X-ray absorption spectroscopy (XAS) a valuable tool for assessing solvent−solute interactions. However, calculating XAS spectra with electronic-structure methods has proven challenging due to delicate interplay between correlation solvation effects. This study provides computational procedure modeling water-solvated ammonia ammonium systems serving as probes. Exploring methodological...

We present the theory and implementation of a novel, fully variational wave function - density functional (DFT) hybrid model, which is applicable to many cases strong correlation. denote this model multiconfigurational self-consistent on-top pair-density (MC-srPDFT). have previously shown how multi-configurational short-range DFT (MC-srDFT) can describe any spin symmetry, also state-specific calculations on excited states. However, srDFT part MC-srDFT has some deficiencies that it shares...

We present an efficient and robust fragment-based quantum–classical embedding model capable of accurately capturing effects from complex environments such as proteins nucleic acids. This is realized by combining the molecular fractionation with conjugate caps (MFCC) procedure polarizable density (PDE) at level Fock matrix construction. The PDE contributions to core region are constructed using local basis individual fragments rather than supermolecular entire system. Thereby, we avoid...

In this paper, we present the theory and implementation of nuclear magnetic resonance shielding constants with gauge-including atomic orbitals for hybrid multiconfigurational short-range density functional model. As a special case, also includes Hartree-Fock srDFT (HF-srDFT). Choosing complete-active space (CAS) wave function as parameterization function, investigate how well CAS-srDFT reproduces experimental trends compared to DFT complete active self-consistent field (CASSCF). Calculations...

Transition metal ions play crucial roles in the structure and function of numerous proteins, contributing to essential biological processes such as catalysis, electron transfer, oxygen binding. However, accurately modeling electronic properties metalloproteins poses significant challenges due complex nature their configurations strong correlation effects. Multiconfigurational quantum chemistry methods are, principle, most appropriate tools for addressing these challenges, offering capability...

We present an efficient and robust fragment-based quantum–classical embedding model capable of accurately capturing effects from complex environments such as proteins nucleic acids. This is realized by combining the molecular fractionation with conjugate caps (MFCC) procedure polarizable density (PDE) at level Fock matrix construction. Thereby we avoid complications associated application fragmentation on environment quantities matrices orbital energies. analyze performance resulting in...

We present an efficient and robust fragment-based quantum–classical embedding model capable of accurately capturing effects from complex environments such as proteins nucleic acids. This is realized by combining the molecular fractionation with conjugate caps (MFCC) procedure polarizable density (PDE) at level Fock matrix construction. The core region constructed using local basis individual fragments rather than supermolecular entire system. Thereby, we avoid complications associated...

We present an efficient and robust fragment-based quantum–classical embedding model capable of accurately capturing effects from complex environments such as proteins nucleic acids. This is realized by combining the molecular fractionation with conjugate caps (MFCC) procedure polarizable density (PDE) at level Fock matrix construction. The core region constructed using local basis individual fragments rather than supermolecular entire system. Thereby, we avoid complications associated...

We extend the polarizable density embedding (PDE) model to support calculation of nuclear magnetic resonance (NMR) shielding constants using gauge-including atomic orbitals (GIAOs) within a functional theory (DFT) framework. The PDE divides total system into fragments, describing some by quantum mechanics (QM) and others through an model. uses anisotropic polarizabilities, inter-fragment two-electron Coulomb integrals, non-local repulsion operator emulate QM effects. terms involving...