Ab initio quantum chemistry methods

About: Ab initio quantum chemistry methods is a research topic. Over the lifetime, 24413 publications have been published within this topic receiving 740820 citations. The topic is also known as: Ab initio method & Ab initio molecular orbital method.

Interatomic potentials for monoatomic metals from experimental data and ab initio calculations

Abstract: We demonstrate an approach to the development of many-body interatomic potentials for monoatomic metals with improved accuracy and reliability. The functional form of the potentials is that of the embedded-atom method, but the interesting features are as follows: (1) The database used for the development of a potential includes both experimental data and a large set of energies of different alternative crystalline structures of the material generated by ab initio calculations. We introduce a rescaling of interatomic distances in an attempt to improve the compatibility between experimental and ab initio data. (2) The optimum parametrization of the potential for the given database is obtained by alternating the fitting and testing steps. The testing step includes a comparison between the ab initio structural energies and those predicted by the potential. This strategy allows us to achieve the best accuracy of fitting within the intrinsic limitations of the potential model. Using this approach we develop reliable interatomic potentials for Al and Ni. The potentials accurately reproduce basic equilibrium properties of these metals, the elastic constants, the phonon-dispersion curves, the vacancy formation and migration energies, the stacking fault energies, and the surface energies. They also predict the right relative stability of different alternative structures with coordination numbers ranging from 12 to 4. The potentials are expected to be easily transferable to different local environments encountered in atomistic simulations of lattice defects.

Estimates of the Ab Initio Limit for π−π Interactions: The Benzene Dimer

Abstract: State-of-the-art electronic structure methods have been applied to the simplest prototype of aromatic π−π interactions, the benzene dimer. By comparison to results with a large aug-cc-pVTZ basis set, we demonstrate that more modest basis sets such as aug-cc-pVDZ are sufficient for geometry optimizations of intermolecular parameters at the second-order Moller−Plesset perturbation theory (MP2) level. However, basis sets even larger than aug-cc-pVTZ are important for accurate binding energies. The complete basis set MP2 binding energies, estimated by explicitly correlated MP2−R12/A techniques, are significantly larger in magnitude than previous estimates. When corrected for higher-order correlation effects via coupled cluster with singles, doubles, and perturbative triples [CCSD(T)], the binding energies De (D0) for the sandwich, T-shaped, and parallel-displaced configurations are found to be 1.8 (2.0), 2.7 (2.4), and 2.8 (2.7) kcal mol-1, respectively.

Is coupled cluster singles and doubles (CCSD) more computationally intensive than quadratic configuration interaction (QCISD)

Abstract: It is shown that the recently proposed QCI method including all single and double substitutions has essentially the same computational requirements as the more complete CCSD approach. If properly formulated, the CCSD equations contain at most quadratic terms in the excitation amplitudes.

Theory and applications of computational chemistry : the first forty years

Abstract: Computing Technologies, Theories, and Algorithms. The Making of 40 Years and More of Theoretical and Computational. A Dynamical, Time-Dependent View of Molecular Theory. Computation of Non-covalent Binding. Electrodynamics in Computational Chemistry. Variational Transition State. Attempting to Simulate Large Molecular Systems. The Beginnings of Coupled Cluster Theory: An Eyewitness Account. Controlling Quantum Phenomena with Photonic Reagents. First-Principles Calculations of Anharmonic Vibrational Spectroscopy of Large Molecules. Finding Minima, Transition States, and Following Reaction Pathways on Ab Initio Potential Energy Surfaces. Progress in the Quantum Description of Vibrational Motion of Polyatomic Molecules. Toward Accurate Computations in Photobiology. The Nature of the Chemical Bond in the Light of an Energy Decomposition Analysis. Superoperator Many-body Theory of Molecular Currents: Non-equilibrium Green Functions in Real Time. Role of Computational Chemistry in the Theory of Unimolecular Reaction Rates. Molecular Dynamics: An Account of its Evolution. Equations of Motion (EOM) Methods for Computing Electron Affinities and Ionization Potentials. Multireference Coupled Cluster Method Based on the Brillouin-Wigner Perturbation Theory. Electronic Structure: The Momentum Perspective. Recent Advances in ab initio, DFT, and Relativistic Electronic Structure Theory . Semiempirical Quantum-Chemical Methods in Computational Chemistry. Size-consistent State-specific Multi-reference Methods: A Survey of Some Recent Developments. The Valence Bond Diagram Approach - A Paradigm for Chemical Reactivity. Development of Approximate Exchange-Correlation Functionals. Multiconfigurational Quantum Chemistry. Concepts of Perturbation, Orbital interaction, Orbital Mixing and Orbital Occupation. G2, G3 and Associated Quantum Chemical Models for Accurate Theoretical Thermochemistry. Factors that Affect Conductance at the Molecular Level. The CH O Hydrogen Bond. A Historical Account. Ab Initio and DFT Calculations on the Cope Rearrangement, a Reaction with a Chameleonic Transition State. High-Temperature Quantum Chemical Molecular Dynamics Simulations of Carbon Nanostructure Self-Assembly Processes. Computational Chemistry of Isomeric Fullerenes and Endofullerenes. On the importance of Many-Body Forces in Clusters and Condensed Phase. Clusters to Functional Molecules, Nanomaterials, and Molecular Devices: Theoretical Exploration. Monte Carlo Simulations of the Finite Temperature Properties of (H2O)6. Computational Quantum Chemistry on Polymer Chains: Aspects of the Last Half Century. Forty Years of Ab Initio Calculations on Intermolecular. Applied Density Functional Theory and the deMon Codes 1964 to 2004. SAC-CI Method Applied to Molecular Spectroscopy. Forty Years of Fenske-Hall Molecular Orbital Theory. Advances in Electronic Structure Theory: GAMESS a Decade Later. How and Why Coupled-Cluster Theory Became the Preeminent Method in Ab initio Quantum Chemistry.