A5033633287- Advanced Chemical Physics Studies
- Inorganic Fluorides and Related Compounds
- Spectroscopy and Quantum Chemical Studies
- Molecular Spectroscopy and Structure
- Synthesis and characterization of novel inorganic/organometallic compounds
- Organometallic Complex Synthesis and Catalysis
- Atmospheric Ozone and Climate
- Molecular Junctions and Nanostructures
- Photochemistry and Electron Transfer Studies
- Atmospheric chemistry and aerosols
- Crystallography and molecular interactions
- Inorganic Chemistry and Materials
- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- Synthesis and Properties of Aromatic Compounds
- Spectroscopy and Laser Applications
- Molecular spectroscopy and chirality
- Various Chemistry Research Topics
- Catalysis and Oxidation Reactions
- Organoboron and organosilicon chemistry
- Inorganic and Organometallic Chemistry
- Magnetism in coordination complexes
- Free Radicals and Antioxidants
- DNA and Nucleic Acid Chemistry
- Quantum, superfluid, helium dynamics
University of Georgia
2016-2025
Georgia Institute of Technology
2022-2023
Institute of Organic Chemistry with Centre of Phytochemistry
2020
Bulgarian Academy of Sciences
2020
Sofia University "St. Kliment Ohridski"
2002-2016
South China Normal University
2007-2015
Piedmont Athens Regional
2014
Freie Universität Berlin
2014
Soochow University
2014
Friedrich-Alexander-Universität Erlangen-Nürnberg
1993-2013
The closed-shell CCSD equations are reformulated in order to achieve superior computational efficiency. Using a spin adaptation scheme based on the unitary group approach (UGA), we have obtained new set of that greatly improves our previous formulation. Based this also derived for configuration interaction including all single and double excitations (CISD) case. Both methods been implemented tested. For range test cases method is more efficient than earlier method. CISD procedure faster...
It is shown that the recently proposed QCI method including all single and double substitutions has essentially same computational requirements as more complete CCSD approach. If properly formulated, equations contain at most quadratic terms in excitation amplitudes.
Psi4 is an ab initio electronic structure program providing methods such as Hartree-Fock, density functional theory, configuration interaction, and coupled-cluster theory. The 1.1 release represents a major update meant to automate complex tasks, geometry optimization using complete-basis-set extrapolation or focal-point methods. Conversion of the top-level code Python module means that can now be used in workflows alongside other tools. Several new features have been added with aid...
Abstract The Psi4 program is a new approach to modern quantum chemistry, encompassing Hartree–Fock and density‐functional theory configuration interaction coupled cluster. written entirely in C++ relies on infrastructure that has been designed permit high‐efficiency computations of both standard emerging electronic structure methods conventional high‐performance parallel computer architectures. offers flexible user input built the Python scripting language enables experienced users make full...
It is shown that to obtain the (2n)th and (2n+1)th energy gradients, it only necessary solve equations of difficulty nth order coupled perturbed for orbital configuration interaction (CI) parameters. For example, find analytic second third derivatives CI wave functions, first some related equations, effects rotations. Similar results apply gradients energies derived using perturbation theory.
PSI4 is a free and open-source ab initio electronic structure program providing implementations of Hartree-Fock, density functional theory, many-body perturbation configuration interaction, cumulant symmetry-adapted coupled-cluster theory. Most the methods are quite efficient, thanks to fitting multi-core parallelism. The hybrid C++ Python, calculations may be run with very simple text files or using Python API, facilitating post-processing complex workflows; method developers also have...
Dative, or nonoxidative, ligand coordination is common in transition metal complexes; however, this bonding motif rare compounds of main group elements the formal oxidation state zero. Here, we report that potassium graphite reduction neutral hypervalent silicon-carbene complex L:SiCl 4 {where L: is:C[N(2,6-Pr i 2 -C 6 H 3 )CH] and Pr isopropyl} produces L:(Cl)Si–Si(Cl):L, a carbene-stabilized bis-silylene, L:Si=Si:L, diatomic silicon molecule with Si atoms The Si-Si bond distance 2.2294 ±...
The convergence of ab initio predictions to the one- and n-particle limits has been systematically explored for several conformational energy prototypes: inversion barriers ammonia, water, isocyanic acid, torsional barrier ethane, E/Z rotamer separation formic linearity silicon dicarbide. Explicit results were obtained with atomic-orbital basis sets as large [7s6p5d4f3g2h1i/6s5p4d3f2g1h] electron correlation treatments extensive fifth-order Mo/ller–Plesset perturbation theory (MP5), full...
The structures and binding energies of the complexes (H2O)2, (H2O)2H+, (HF)2, (HF)2H+, F2H−, (NH3)2 have been examined using much higher levels theory than has previously applied to these systems. These methods including large basis sets full optimization with effects electron correlation included, are known give single bond an accuracy about 2 kcal mol−1 found in this study excellent agreement extensive experimental data available for hydrogen fluoride water dimers. Cs open form ammonia...
The syntheses and molecular structures of four compounds are reported: 1 (RBBr3), 2 (R(H)2B−B(H)2R), 3 (R(H)BB(H)R), 4 (RBH3) (R = :C{N(2,6-Pri2C6H3)CH}2). These were characterized by single-crystal X-ray diffraction, 1H 11B NMR, elemental analyses. Compounds prepared the KC8 reduction in Et2O. Compound is first structurally neutral diborene (mean BB: 1.560(18) Å). nature BB double bond was delineated DFT computations.
The C2H5• + O2 reaction, central to ethane oxidation and thus of fundamental importance hydrocarbon combustion chemistry, has been examined in detail via highly sophisticated electronic structure methods. geometries, energies, harmonic vibrational frequencies the reactants, transition states, intermediates, products for reaction ethyl radical (X̃ 2A') with (X 3 , a 1Δg) have investigated using CCSD CCSD(T) ab initio methods basis sets ranging quality from double-zeta plus polarization (DZP)...
The prediction of the diagonal correction to Born–Oppenheimer approximation is now possible by ab initio analytic methods, as has recently been shown Yarkony and Lengsfield. At general restricted Hartree–Fock (GRHF) level approximation, procedure straightforward: solutions coupled perturbed equations (CPHF) some overlap integrals are all that required. This evaluated for a series small molecules with various basis sets: H2O, H2O+, CH2, HCF, H+5, F2. It interesting observe value this (0.11...
The theory for the analytic evaluation of energy gradients coupled cluster (CC) wave functions is presented. In particular, explicit expressions gradient CC singles and doubles (CCSD) function a closed-shell restricted Hartree–Fock reference determinant are presented shown to scale as N6 where N one-electron number atomic basis molecular system. Thus CCSD found be same magnitude in computational cost configuration interaction (CISD) function. Applications this method water molecule...
The potassium graphite reduction of L:PCl3 leads to the formation carbene-stabilized diphosphorus molecules, L:P−P:L, 1 (L: = :C{N(2,6-Pr i 2C6H3)CH}2) and 2 :C{N(2,4,6-Me3C6H2)CH}2), respectively. nature bonding in was delineated by DFT computations.
Recent theoretical research by Paldus and Shavitt has strongly suggested that the unitary group approach to many body problem may be useful in molecular electronic problems. The graphical (GUGA) now been developed into an extraordinarily powerful method. theoretical/methodological contributions made here include a solution of upper walk problem, restriction configuration space employed multireference interacting space, restructuring Hamiltonian terms loop types. Several test calculations are...
A single and double excitation coupled cluster (CCSD) method restricted to closed-shell configuration reference functions is described in explicit detail. Some significant simplifications resulting from the restriction systems are exploited achieve maximum computational efficiency. Comparisons for energetic results requirements made with interaction (CISD) method. The specific molecules considered include N2, H2O, H3O+, H5O+2, HSOH, s-tetrazine (C2N4H2).
The hole states of O 2 +, obtained by ionization the oxygen molecule, have been examined theoretically in three approximations: (i) frozen orbital approximation, which consists single configuration calculations terms Hartree-Fock orbitals for neutral O2 molecule; (ii) direct hole-state g or u inversion symmetry is imposed on each molecular orbital; (iii) without restriction (ii). For 1s 4Σ− state approximations yield following potentials: 563.5 eV; 554.4 542.0 eV. experimental potential...