A5041373282- Advanced Chemical Physics Studies
- Spectroscopy and Quantum Chemical Studies
- Quantum, superfluid, helium dynamics
- Physics of Superconductivity and Magnetism
- Advanced NMR Techniques and Applications
- Inorganic Fluorides and Related Compounds
- Photochemistry and Electron Transfer Studies
- Molecular Junctions and Nanostructures
- High-pressure geophysics and materials
- Molecular Spectroscopy and Structure
- Advanced Physical and Chemical Molecular Interactions
- Solid-state spectroscopy and crystallography
- Atmospheric Ozone and Climate
- Molecular spectroscopy and chirality
- Cold Atom Physics and Bose-Einstein Condensates
- Quantum and electron transport phenomena
- Catalysis and Oxidation Reactions
- Machine Learning in Materials Science
- Spectroscopy and Laser Applications
- Crystallography and molecular interactions
- Catalytic Processes in Materials Science
- Atmospheric chemistry and aerosols
- Surface and Thin Film Phenomena
- Free Radicals and Antioxidants
- Parallel Computing and Optimization Techniques
University of Illinois Urbana-Champaign
2016-2025
Tokyo Women's Medical University
2024-2025
Gifu University
2019
Japan Science and Technology Agency
2013-2018
Cardiff University
2017
Auburn University
2017
Max Planck Institute for Solid State Research
2017
Kobe University
2017
International University of the Caribbean
2015
University of Florida
2002-2012
Q-Chem 2.0 is a new release of an electronic structure program package, capable performing first principles calculations on the ground and excited states molecules using both density functional theory wave function-based methods. A review technical features contained within presented. This article contains brief descriptive discussions key physical all algorithms theoretical models, together with sample that illustrate their performance. © 2000 John Wiley & Sons, Inc. J Comput Chem 21: 1532–1548,
Specialized computational chemistry packages have permanently reshaped the landscape of chemical and materials science by providing tools to support guide experimental efforts for prediction atomistic electronic properties. In this regard, structure played a special role using first-principle-driven methodologies model complex processes. Over past few decades, rapid development computing technologies tremendous increase in power offered unique chance study transformations sophisticated...
We have developed a symbolic manipulation program and generator (tensor contraction engine or TCE) that abstracts automates the time-consuming, error-prone processes of deriving working equations well-defined model second-quantized many-electron theories synthesizing efficient parallel computer programs on basis these equations. Provided an ansatz theory model, TCE performs valid contractions creation annihilation operators according to Wick's theorem, consolidates identical terms, reduces...
The exact orbital-dependent exchange (EXX) energy formalism within the linear-combination-of-atomic-orbital Kohn-Sham density functional theory for polyatomic molecules is presented and implemented. energies occupied orbital obtained from EXX are very close to corresponding Hartree-Fock (HF) values, whereas unoccupied significantly lower than HF values. We demonstrate that current approximate correlation functionals deteriorate when combined with EXX.
Time-dependent density functional theory (TDDFT) is applied to calculate vertical excitation energies of trans-1,3-butadiene, trans−trans-1,3,5-hexatriene, all-trans-1,3,5,7-octatetraene, and all-trans-1,3,5,7,9-decapentaene. Attachment detachment densities for transitions in butadiene decapentaene from the ground state 2 1Ag 1 1Bu excited states are also calculated analyzed. Based on comparisons with experimental results high level ab initio calculations literature, significant improvement...
The equation-of-motion coupled-cluster (EOM-CC) methods truncated after double, triple, or quadruple cluster and linear excitation operators (EOM-CCSD, EOM-CCSDT, EOM-CCSDTQ) have been derived implemented into parallel execution programs. They compute energies, excited-state dipole moments, transition moments of closed- open-shell systems, taking advantage spin, spatial (real Abelian), permutation symmetries simultaneously fully (within the spin-orbital formalisms). related Lambda equation...
Time-dependent density functional theory (TDDFT) and its modification, the Tamm–Dancoff approximation to TDDFT, are employed calculate electronic excitation energies oscillator strengths for a series of polycyclic aromatic hydrocarbon radical cations. For cations naphthalene anthracene, TDDFT using Becke–Lee–Yang–Parr 6-31G** basis set provides that roughly within 0.3 eV experimental data. The assignments electron transitions proposed by accord with previous made accurate ab initio...
A general formalism for time-dependent linear response theory is presented within the framework of linear-combination-of-atomic-orbital crystalline orbital electronic excited states infinite one-dimensional lattices (polymers). The encompasses those Hartree–Fock (TDHF), density functional (TDDFT), and configuration interaction singles (CIS) (as Tamm–Dancoff approximation to TDHF) as particular cases. These single-excitation theories are implemented by using a trial-vector algorithm, such...
This paper provides an overview of a program synthesis system for class quantum chemistry computations. These computations are expressible as set tensor contractions and arise in electronic structure modeling. The input to the is high-level specification computation, from which can synthesize high-performance parallel code tailored characteristics target architecture. Several components described, focusing on performance optimization issues that they address.
We report on the comparison of electronic and photophysical properties a series related donor–acceptor–donor oligomers incorporating previously known 2H-benzo[d][1,2,3]triazole (BTz) moiety as acceptor recently reported BTzTD acceptor, hybrid BTz 2,1,3-benzothiadiazole (BTD). Although often implied in polymer literature that has good character, we show this is best described weak acceptor. present electrochemical, computational, evidence supporting our assertion strong electron while...
A procedure to determine optimal vibrational coordinates is developed on the basis of an earlier idea Thompson and Truhlar [J. Chem. Phys. 77, 3031 (1982)]10.1063/1.444226. For a given molecule, these are defined as unitary transform normal that minimizes energy self-consistent-field (VSCF) method for ground state. They justified by fact VSCF in becomes exact two limiting cases: harmonic oscillators, where optimized normal, noninteracting anharmonic which localized individual oscillators....
Abstract A direct, simultaneous calculation of properties a liquid using an ab initio electron-correlated theory has long been unthinkable. Here we present structural, dynamical and response water calculated by molecular dynamics the embedded-fragment spin-component-scaled second-order many-body perturbation method with aug-cc-pVDZ basis set. This level is chosen as it accurately inexpensively reproduces dimer potential energy surface from coupled-cluster singles, doubles noniterative...
Local (multiplicative) effective exchange potentials obtained from the linear-combination- of-atomic-orbital (LCAO) optimized potential (OEP) method are frequently unrealistic in that they tend to exhibit wrong asymptotic behavior (although formally should have correct behavior) and also assume unphysical rapid oscillations around nuclei. We give an algebraic proof that, with infinity of orbitals, kernel OEP integral equation has one only singularity associated a constant hence determines...
We develop a combined coupled-cluster (CC) or equation-of-motion (EOM-CC) theory and Rayleigh–Schrödinger perturbation on the basis of expansion similarity-transformed Hamiltonian H̄=exp(−T)H exp(T). This generates series perturbative corrections to any complete CC EOM-CC models hence hierarchy methods designated by CC(m)PT(n) EOM-CC(m)PT(n). These systematically approach full configuration interaction (FCI) as order (n) increases and/or cluster linear excitation operators become closer (m...
From coupled-cluster theory and many-body perturbation we derive the local exchange-correlation potential of density functional in an orbital dependent form. We show relationship between approach theory, connections comparisons with our previous second-order correlation [OEP-MBPT(2) (OEP—optimized effective potential)] [I. Grabowski, S. Hirata, Ivanov, R. J. Bartlett, Chem. Phys. 116, 4415 (2002)]. Starting from a general theoretical framework based on condition Kohn–Sham define rigorous...
Various approximations combining coupled-cluster (CC) and many-body perturbation theories have been derived implemented into the parallel execution programs that take account spin, spatial (real Abelian), permutation symmetries are applicable to closed- open-shell molecules. The models range from CCSD(T), CCSD[T], CCSD(2)(T), CCSD(2)(TQ), CCSDT(2)(Q) methods completely renormalized (CR) CCSD(T) CCSD[T] approaches, where CCSD (CCSDT) stands for CC method with connected single double (single,...
Coupled-cluster theory with connected single and double excitation operators (CCSD) related approximations, such as linearized CCSD, quadratic configuration interaction operators, coupled-cluster operator (CCD), CCD, approximate second- third-order many-body perturbation theories, are formulated implemented for infinitely extended one-dimensional systems (polymers), on the basis of periodic boundary conditions distance-based screening integrals, density matrix elements, amplitudes. The...
Using the optimized effective potential (OEP) method in conjunction with an orbital-dependent correlation functional developed on basis of second-order many-body perturbation theory [MBPT(2)], we perform ab initio correlated density calculations. Unlike other methods, this offers first approximation a converging series approximations analogous to that wave function theory. The OEP-MBPT(2) potentials helium isoelectronic and neon atom are excellent agreement prior quantum Monte Carlo (QMC)...
An efficient and accurate electronic structure method for clusters of weakly interacting molecules has been proposed, on the basis pair-interaction Kitaura et al., combined with density functional, many-body perturbation, coupled-cluster, equation-of-motion configuration-interaction singles, time-dependent functional theories. The retains one- two-body (and, if necessary, also three-body) Coulomb, exchange, correlation energies exactly higher-order Coulomb in leading order multipole...
A quasi-degenerate perturbation method with vibrational self-consistent field (VSCF) reference wavefunction is developed. It simultaneously accounts for strong anharmonic mode–mode coupling among a few states (static correlation) by configuration interaction theory and weak vast number of the other (dynamic theory. general formula derived based on van Vleck An algorithm that selects compact set most important VSCF configurations which contribute to static correlation proposed scheme limit...
Compact algebraic equations defining the equation-of-motion coupled-cluster (EOM-CC) methods for ionization potentials (IP-EOM-CC) have been derived and computer implemented by virtue of a symbolic algebra system largely automating these processes. Models with connected cluster excitation operators truncated after double, triple, or quadruple level linear two-hole-one-particle (2h1p), three-hole-two-particle (3h2p), four-hole-three-particle (4h3p) (abbreviated as IP-EOM-CCSD, CCSDT, CCSDTQ,...