A5052766760- Spectroscopy and Quantum Chemical Studies
- Advanced Chemical Physics Studies
- Photochemistry and Electron Transfer Studies
- Molecular Junctions and Nanostructures
- Electrochemical Analysis and Applications
- Machine Learning in Materials Science
- Chemical Reactions and Isotopes
- Protein Structure and Dynamics
- Quantum, superfluid, helium dynamics
- Crystallography and molecular interactions
- DNA and Nucleic Acid Chemistry
- Molecular spectroscopy and chirality
- Inorganic Fluorides and Related Compounds
- Advanced NMR Techniques and Applications
- Asymmetric Hydrogenation and Catalysis
- Coordination Chemistry and Organometallics
- Catalytic Processes in Materials Science
- Analytical Chemistry and Sensors
- Synthesis and Biological Evaluation
- Catalytic Cross-Coupling Reactions
- Asymmetric Synthesis and Catalysis
- Chemical Reaction Mechanisms
- Chemical Synthesis and Analysis
- Electron Spin Resonance Studies
- Advanced Thermodynamics and Statistical Mechanics
The Ohio State University
2016-2025
University of California, Berkeley
2004-2019
Lawrence Berkeley National Laboratory
2019
Sanofi (Turkey)
2015
University of Surrey
2011
Sanofi (United Kingdom)
2001-2011
Purdue University West Lafayette
2010
University of Southern California
2010
Ames National Laboratory
2010
Iowa State University
2010
We introduce a hybrid density functional that asymptotically incorporates full Hartree-Fock exchange, based on the long-range-corrected exchange-hole model of Henderson et al. [J. Chem. Phys. 128, 194105 (2008)]. The performance this functional, for ground-state properties and vertical excitation energies within time-dependent theory, is systematically evaluated, optimal values are determined range-separation parameter, omega, fraction short-range exchange. denote new as LRC-omegaPBEh, since...
We present benchmark calculations using several long-range-corrected (LRC) density functionals, in which Hartree–Fock exchange is incorporated asymptotically a range-separated Coulomb operator, while local attenuated an ansatz introduced by Iikura et al. [J. Chem. Phys. 115, 3540 (2001)]. calculate ground-state atomization energies, reaction barriers, ionization and electron affinities, each as function of the range-separation parameter μ. In addition, we excitation energies small-...
Fragment-based quantum chemistry methods are a promising route towards massively parallel electronic structure calculations in large systems. Unfortunately, the literature on this topic consists of bewildering array different methods, with no clear guiding principles to choose amongst them. Here, we introduce conceptual framework that unifies many these ostensibly disparate approaches. The common is based upon an approximate supersystem energy formula for collection intersecting (i.e.,...
This review describes the theory and implementation of implicit solvation models based on continuum electrostatics. Within quantum chemistry this formalism is sometimes synonymous with polarizable model, a particular boundary-element approach to problem defined by Poisson or Poisson-Boltzmann equation, but that moniker belies diversity available methods. work reviews current state-of-the art, emphasis methods rather than applications. The basics electrostatics are described, including...
Since the introduction of fragment molecular orbital method 20 years ago, fragment-based approaches have occupied a small but growing niche in quantum chemistry. These methods decompose large system into subsystems enough to be amenable electronic structure calculations, following which subsystem information is reassembled order approximate an otherwise intractable supersystem calculation. Fragmentation sidesteps steep rise (with respect size) cost ab initio replacing it with distributed...
Electronic structure calculations have been instrumental in providing many important insights into a range of physical and chemical properties various molecular solid-state systems. Their importance to fields, including materials science, sciences, computational chemistry device physics, is underscored by the large fraction available public supercomputing resources devoted these calculations. As we enter exascale era, exciting new opportunities increase simulation numbers, sizes, accuracies...
Abstract The hydrated electron, e – (aq) , has attracted much attention as a central species in radiation chemistry. However, less is known about at the water/air surface, despite its fundamental role electron transfer processes interfaces. Using time-resolved electronic sum-frequency generation spectroscopy, spectrum of interface and dynamics are measured here, following photo-oxidation phenoxide anion. spectral maximum agrees with that for bulk shows orbital density resides predominantly...
Fragment-based quantum chemistry methods offer a means to sidestep the steep nonlinear scaling of electronic structure calculations so that large molecular systems can be investigated using high-level methods. Here, we use fragmentation compute protein-ligand interaction energies in with several thousand atoms, new software platform for managing fragment-based implements screened many-body expansion. Convergence tests minimal-basis semiempirical method (HF-3c) indicate two-body calculations,...
Electronic structure calculations in enzymes converge very slowly with respect to the size of model region that is described using quantum mechanics (QM), requiring hundreds atoms obtain converged results and exhibiting substantial sensitivity (at least smaller models) which amino acids are included QM region. As such, there considerable interest developing automated procedures construct a based on well-defined criteria. However, testing such burdensome due cost large-scale electronic...
Polarizable continuum models (PCMs) are a widely used family of implicit solvent based on reaction-field theory and boundary-element discretization the solute/continuum interface. An often overlooked aspect these theories is that interface typically does not afford continuous potential energy surface for solute. In addition, we show can lead to numerical singularities violations exact variational conditions. To fix problems, introduce switching/Gaussian (SWIG) method, scheme overcomes...
Vertical electronic excitations in model systems representing single- and double-stranded B-DNA are characterized using structure theory, including both time-dependent density functional theory (TD-DFT) correlated wave function techniques. Previous TD-DFT predictions of charge-transfer (CT) states well below the optically bright 1ππ* shown to be artifacts improper long-range behavior standard density-functional exchange approximations, which we rectify here a correction (LRC) procedure. For...
The electronic spectrum of alternant polycyclic aromatic hydrocarbons (PAHs) includes two singlet excited states that are often denoted 1La and 1Lb. Time-dependent density functional theory (TD-DFT) affords reasonable excitation energies for the 1Lb state in such molecules, but severely underestimates fails to reproduce observed trends energy as a function molecular size. Here, we examine performance long-range-corrected (LRC) functionals various PAHs. With an appropriate choice Coulomb...
The lowest few electronic excitations of a π-stacked adenine dimer in its B-DNA geometry are investigated, the gas phase and water cluster, using long-range-corrected version time-dependent density functional theory (TD-DFT) that asymptotically incorporates Hartree−Fock exchange. Long-range correction is shown to eliminate catastrophic underestimation charge-transfer (CT) excitation energies plagues conventional TD-DFT, at expense introducing one adjustable parameter, μ, determines length...
Existence of a hydrated electron as byproduct water radiolysis was established more than 50 years ago, yet this species continues to attract significant attention due its role in radiation chemistry, including DNA damage, and because questions persist regarding detailed structure. This work provides an overview what is known regards the structure spectroscopy electron, both liquid clusters [Formula: see text], latter which provide model systems for how networks accommodate excess electron....
Density‐functional approximations developed in the past decade necessitate use of quadrature grids that are far more dense than those required to integrate older generations functionals. This category difficult‐to‐integrate functionals includes meta‐generalized gradient approximations, which depend on orbital gradients and/or Laplacian density, as well based B97 and popular “Minnesota” class functionals, each contain complicated oscillatory expressions for exchange inhomogeneity factor....
Apparent surface charge, reaction-field solvation models often employ overlapping atomic spheres to represent the solute/continuum boundary. Discretization of solute cavity surface, however, results in a boundary-element method that fails afford continuous potential energy for solute. Several proposed remedies this problem, based upon switching functions grid points and originally introduced conductor-like screening model (COSMO), are generalized here an entire class polarizable continuum...
We report the implementation and evaluation of a perturbative, density-based correction scheme for vertical excitation energies calculated in framework polarizable continuum model (PCM). Because proposed first-order terms depend solely on zeroth-order excited-state density, transfer approach to any configuration interaction-type method is straightforward. Employing algebraic-diagrammatic construction (ADC) up third order as well time-dependent density-functional theory (TD-DFT), we...
Three new data sets for intermolecular interactions, AHB21 anion-neutral dimers, CHB6 cation-neutral and IL16 ion pairs, are assembled here, with complete-basis CCSD(T) results each. These benchmarks then used to evaluate the accuracy of single-exchange approximation that is exchange energies in symmetry-adapted perturbation theory (SAPT), SAPT based on wave function density-functional descriptions monomers evaluated. High-level calculations afford poor these sets, this includes recently...
We present an overview of "XSAPT", a family quantum chemistry methods for noncovalent interactions. These combine efficient, iterative, monomer-based approach to computing many-body polarization interactions with two-body version symmetry-adapted perturbation theory (SAPT). The result is efficient method accurate intermolecular interaction energies in large assemblies such as molecular and ionic clusters, crystals, clathrates, or protein-ligand complexes. As traditional SAPT, the XSAPT...
ConspectusThe past 15 years have witnessed an explosion of activity in the field fragment-based quantum chemistry, whereby ab initio electronic structure calculations are performed on very large systems by decomposing them into a number relatively small subsystem and then reassembling data order to approximate supersystem properties. Most these methods based, at some level, so-called many-body (or "n-body") expansion, which ultimately requires monomers, dimers, ..., n-mers fragments. To...
The nature of π-π interactions has long been debated. term "π-stacking" is considered by some to be a misnomer, in part because overlapping π-electron densities are thought incur steric repulsion, and the physical origins widely-encountered "slip-stacked" motif have variously attributed either sterics or electrostatics, competition with dispersion. Here, we use quantum-mechanical energy decomposition analysis investigate supramolecular complexes polycyclic aromatic hydrocarbons, ranging size...
We revisit the calculation of analytic derivative couplings for configuration interaction singles (CIS), and derive implement these its spin-flip variant first time. Our algorithm is closely related to CIS energy gradient should be straightforward in any quantum chemistry code that has gradients. The additional cost evaluating small comparison gradients two electronic states question. Incorporation an exchange-correlation term provides ad hoc extension this formalism time-dependent density...
Singlet fission proceeds rapidly and with high quantum efficiency in both crystalline tetracene pentacene, which poses a conundrum given that the process is disfavored by electronic energetics. Here, we use an ab initio exciton model to compute nonadiabatic couplings unit cell of order identify modes promote this process. Four intramolecular range 1400-1600 cm-1, are nearly resonant single-exciton/multiexciton energy gap, appear play key role. Ab calculations electron/phonon coupling...
Electronic structure methods based on low-order “n-body” expansions are an increasingly popular means to defeat the highly nonlinear scaling of ab initio quantum chemistry calculations, taking advantage inherently distributable nature numerous subsystem calculations. Here, we examine how finite precision these calculations manifests in applications large systems, this case, a sequence water clusters ranging size up \documentclass[12pt]{minimal}\begin{document}$\rm...