John R. Sabin

Bio: John R. Sabin is an academic researcher from University of Florida. The author has contributed to research in topics: Stopping power (particle radiation) & Ion. The author has an hindex of 29, co-authored 265 publications receiving 4987 citations. Previous affiliations of John R. Sabin include University of Missouri & Queen's University.

On some approximations in applications of Xα theory

Abstract: An approximate Xα functional is proposed from which the charge density fitting equations follow variationally. LCAO Xα calculations on atomic nickel and diatomic hydrogen show the method independent of the fitting (auxiliary) bases to within 0.02 eV. Variational properties associated with both orbital and auxiliary basis set incompleteness are used to approach within 0.2 eV the Xα total energy limit for the nitrogen molecule.

On first‐row diatomic molecules and local density models

Abstract: The total Xα energy accurate to 0.3 eV is computed for H2, B2, C2, N2, O2, CO, and F2. Relative to experiment, the Xα model (α=0.7) is accurate to within ΔRe=0.1 bohr, ΔDe=2 eV, and Δωe=300 cm−1 for these molecules. Except for the lightest first‐row diatomic molecules, the Xα and experimental dissociation energies are bracketed by those of the Hartree–Fock model (from below) and the Local Spin Density model (from above).

Quantum systems in chemistry and physics

Abstract: H.M. Quiney, H. Skaane, and I.P. Grant, Ab Initio Relativistic Quantum Chemistry: Four-Components Good, Two-Components Bad! D.L. Cooper, T. Thorsteinsson, and J. Gerratt, Modern VB Representations of CASSCF Wave Functions and the Fully-Variational Optimization of Modern VB Wave Functions Using the CASVB Strategy. A. Kalemos and A. Mavridis, On the Electronic Structure of ScB+: Ground and Low-Lying Excited States. A. Szarecka, G. Day, P.J. Grout, and S. Wilson, On the Effects of Basis Set Truncation and Electron Correlation in the Conformers of 2-Hydroxy-Acetamide. M. Hoffmann, A. Szarecka, and J. Rychlewski, Gas-Phase Conformational Analysis of (R,R)-Tartaric Acid, Its Diamide, N,N,N',N'-Tetramethyldiamide and Model. C. Petrongolo, Recent Theoretical Developments in Conical-Intersection Effects in Triatomic Spectra. Y.G. Smeyers, M.L. Senent, and M. Villa, Ab Initio Determination of Band Structures of Vibrational Spectra of Non-Rigid Molecules: Applications to Methylamine and Dimethylamine. R.G. Woolley, Gauge Invariance and Multipole Moments. I. Martin, C. Lavin, Y. Perez-Delgado, J. Karwowski, and G.H.F. Diercksen, Vertical Electron Transitions in Rydberg Radicals. V. Veniard, R. Taieb, and A. Maquet, Time-Dependent Quantum Treatment of Two-Colour Multiphoton Ionization Using a Strong Laser Pulse and High-Order Harmonic Radiation. M. Bylicki, Methods Involving Complex Coordinates Applied to Atoms. C. Amovilli, V. Barone, R. Cammi, E. Cances, M. Cossi, B. Mennucci, C.S. Pomelli, and J. Tomasi, Recent Advances in the Description of Solvent Effects with the Polarization Continuum Model. M. Raimondi, A. Famulari, E. Gianinetti, M. Sorani, R. Specchio, and I. Vandoni, New Ab Initio VB Interaction Potential for Molecular Dynamics Simulation of Liquid Water. G.K.A. Keith, P.J. Grout, and S. Wilson, Systematic Sequences of Even-Tempered Gaussian Primatives for Diatomic Molecules in Solution: A Preliminary Study Using Continuum Solvation Models. J. Lingerberg, Beyond the Transition State Treatment. Subject Index.

Total Energy in the Multiple Scattering Formalism: Application to the Water Molecule

Abstract: A scheme for obtaining the statistical total energy in the multiple scattering formalism is presented. Calculations are then carried out on the water molecule, which has been thoroughly investigated by ab initio LCAO MO SCF and experimental methods, in order to test the reliability of the method. The one‐electron energies, ionization potentials, and vibrational potential curves are reported. Some advantages and limitations of the method are discussed in light of these results.

The M06 suite of density functionals for main group thermochemistry, thermochemical kinetics, noncovalent interactions, excited states, and transition elements: two new functionals and systematic testing of four M06-class functionals and 12 other functionals

Abstract: We present two new hybrid meta exchange- correlation functionals, called M06 and M06-2X. The M06 functional is parametrized including both transition metals and nonmetals, whereas the M06-2X functional is a high-nonlocality functional with double the amount of nonlocal exchange (2X), and it is parametrized only for nonmetals.The functionals, along with the previously published M06-L local functional and the M06-HF full-Hartree–Fock functionals, constitute the M06 suite of complementary functionals. We assess these four functionals by comparing their performance to that of 12 other functionals and Hartree–Fock theory for 403 energetic data in 29 diverse databases, including ten databases for thermochemistry, four databases for kinetics, eight databases for noncovalent interactions, three databases for transition metal bonding, one database for metal atom excitation energies, and three databases for molecular excitation energies. We also illustrate the performance of these 17 methods for three databases containing 40 bond lengths and for databases containing 38 vibrational frequencies and 15 vibrational zero point energies. We recommend the M06-2X functional for applications involving main-group thermochemistry, kinetics, noncovalent interactions, and electronic excitation energies to valence and Rydberg states. We recommend the M06 functional for application in organometallic and inorganometallic chemistry and for noncovalent interactions.

Self-interaction correction to density-functional approximations for many-electron systems

Abstract: The exact density functional for the ground-state energy is strictly self-interaction-free (i.e., orbitals demonstrably do not self-interact), but many approximations to it, including the local-spin-density (LSD) approximation for exchange and correlation, are not. We present two related methods for the self-interaction correction (SIC) of any density functional for the energy; correction of the self-consistent one-electron potenial follows naturally from the variational principle. Both methods are sanctioned by the Hohenberg-Kohn theorem. Although the first method introduces an orbital-dependent single-particle potential, the second involves a local potential as in the Kohn-Sham scheme. We apply the first method to LSD and show that it properly conserves the number content of the exchange-correlation hole, while substantially improving the description of its shape. We apply this method to a number of physical problems, where the uncorrected LSD approach produces systematic errors. We find systematic improvements, qualitative as well as quantitative, from this simple correction. Benefits of SIC in atomic calculations include (i) improved values for the total energy and for the separate exchange and correlation pieces of it, (ii) accurate binding energies of negative ions, which are wrongly unstable in LSD, (iii) more accurate electron densities, (iv) orbital eigenvalues that closely approximate physical removal energies, including relaxation, and (v) correct longrange behavior of the potential and density. It appears that SIC can also remedy the LSD underestimate of the band gaps in insulators (as shown by numerical calculations for the rare-gas solids and CuCl), and the LSD overestimate of the cohesive energies of transition metals. The LSD spin splitting in atomic Ni and $s\ensuremath{-}d$ interconfigurational energies of transition elements are almost unchanged by SIC. We also discuss the admissibility of fractional occupation numbers, and present a parametrization of the electron-gas correlation energy at any density, based on the recent results of Ceperley and Alder.

An all‐electron numerical method for solving the local density functional for polyatomic molecules

Abstract: A method for accurate and efficient local density functional calculations (LDF) on molecules is described and presented with results The method, Dmol for short, uses fast convergent three‐dimensional numerical integrations to calculate the matrix elements occurring in the Ritz variation method The flexibility of the integration technique opens the way to use the most efficient variational basis sets A practical choice of numerical basis sets is shown with a built‐in capability to reach the LDF dissociation limit exactly Dmol includes also an efficient, exact approach for calculating the electrostatic potential Results on small molecules illustrate present accuracy and error properties of the method Computational effort for this method grows to leading order with the cube of the molecule size Except for the solution of an algebraic eigenvalue problem the method can be refined to quadratic growth for large molecules

Chemistry with ADF

Abstract: We present the theoretical and technical foundations of the Amsterdam Density Functional (ADF) program with a survey of the characteristics of the code (numerical integration, density fitting for the Coulomb potential, and STO basis functions). Recent developments enhance the efficiency of ADF (e.g., parallelization, near order-N scaling, QM/MM) and its functionality (e.g., NMR chemical shifts, COSMO solvent effects, ZORA relativistic method, excitation energies, frequency-dependent (hyper)polarizabilities, atomic VDD charges). In the Applications section we discuss the physical model of the electronic structure and the chemical bond, i.e., the Kohn–Sham molecular orbital (MO) theory, and illustrate the power of the Kohn–Sham MO model in conjunction with the ADF-typical fragment approach to quantitatively understand and predict chemical phenomena. We review the “Activation-strain TS interaction” (ATS) model of chemical reactivity as a conceptual framework for understanding how activation barriers of various types of (competing) reaction mechanisms arise and how they may be controlled, for example, in organic chemistry or homogeneous catalysis. Finally, we include a brief discussion of exemplary applications in the field of biochemistry (structure and bonding of DNA) and of time-dependent density functional theory (TDDFT) to indicate how this development further reinforces the ADF tools for the analysis of chemical phenomena. © 2001 John Wiley & Sons, Inc. J Comput Chem 22: 931–967, 2001

SRIM – The stopping and range of ions in matter (2010)

Abstract: SRIM is a software package concerning the S topping and R ange of I ons in M atter. Since its introduction in 1985, major upgrades are made about every six years. Currently, more than 700 scientific citations are made to SRIM every year. For SRIM-2010 , the following major improvements have been made: (1) About 2800 new experimental stopping powers were added to the database, increasing it to over 28,000 stopping values. (2) Improved corrections were made for the stopping of ions in compounds. (3) New heavy ion stopping calculations have led to significant improvements on SRIM stopping accuracy. (4) A self-contained SRIM module has been included to allow SRIM stopping and range values to be controlled and read by other software applications. (5) Individual interatomic potentials have been included for all ion/atom collisions, and these potentials are now included in the SRIM package. A full catalog of stopping power plots can be downloaded at www.SRIM.org . Over 500 plots show the accuracy of the stopping and ranges produced by SRIM along with 27,000 experimental data points. References to the citations which reported the experimental data are included.