A detailed analysis of a method proposed earlier for calculating good approximation to the electronic correlation energy is presented here. The principal advantages this compared usual CI techniques are discussed.

The Ne photoabsorption spectrum in the region of K edge has been measured with unprecedented energy resolution. results have interpreted by using an ab initio method that predicts natural linewidths, as well relative intensities and positions different $1\stackrel{\ensuremath{\rightarrow}}{s}\mathrm{np}$ $(3<~n<~6)$ transitions. remarkable agreement between theory experiment improves spectroscopic characterization these inner-shell excited states where only electron-energy-loss...

In this paper, we investigate band-structure effects on the transport properties of ultrascaled silicon nanowire FETs operating under quantum-ballistic conditions. More specifically, expand dispersion relationship epsiv(kappa) in a power series up to third order kappa <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and generate corresponding higher operator be used within single-electron Hamiltonian for solution Schrodinger equation. We...

Abstract The minimum‐energy geometrical structure of the regioregular head‐to‐tail poly(3‐hexylthiophene) (rr‐HT‐P3HT) polymer has been addressed by means density functional theory (DFT) calculations which include long‐range (van der Waals) interactions. problem P3HT debated in literature last decades mainly for what concerns arrangement alkyl side chains and type content crystalline primitive cell. main result our is that energetically favored at T = 0 K corresponds to polythiophene with...

The possibility of an a posteriori correction to the Hartree-Fock total energy periodic systems through use density functional for correlation is explored. proposed by Colle and Salvetti [Theor. Chim. Acta 37, 329 (1975)] has been adopted, which presents many attractive features: For example, electronic self-interaction excluded (no one electron systems). Computational details calculation from ab initio crystalline orbital linear combination atomic are reported. Quite good results obtained...

Absolute cross sections for the ($p,n$) reactions on $^{63}\mathrm{Cu}$, $^{65}\mathrm{Cu}$, and $^{107}\mathrm{Ag}$ at proton energies from 2.5 to 25 MeV were determined by activation method. Metal foil targets of natural isotopic abundance used; therefore, results $^{63}\mathrm{Zn}$ above 22.3 $^{107}\mathrm{Cd}$ 18.8 include contributions ($p,3n$) reactions. Beam intensities measured with a Faraday cup. Disintegration rates product nuclei assaying their $\ensuremath{\gamma}$ rays...

The Colle–Salvetti method for calculating the correlation energy [Theor. Chim. Acta 37, 329 (1975)] is generalized to treat cases in which reference function not a Hartree–Fock one, but many-determinant wave function. Through calculations on atoms and diatomic molecules it shown that this approach gives ‘‘experimental,’’ non-relativistic electronic at millihartree level of accuracy also internuclear distances far from equilibrium positions.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXT(1S)-1-(Aminomethyl)-2-(arylacetyl)-1,2,3,4-tetrahydroisoquinoline and heterocycle-condensed tetrahydropyridine derivatives: members of a novel class very potent .kappa. opioid analgesicsVittorio Vecchietti, Geoffrey D. Clarke, Roberto Colle, Giuseppe Giardina, Petrone, Massimo SbacchiCite this: J. Med. Chem. 1991, 34, 8, 2624–2633Publication Date (Print):August 1, 1991Publication History Published online1 May 2002Published inissue 1 August...

We present the absorption coefficient alpha(omega), transverse dielectric function epsilon(omega), optical conductivity sigma(omega), and reflectance R(omega) calculated for an emeraldine salt conducting polymer in its crystalline 3D polaronic structure. utilize Kohn-Sham density functional theory (DFT) electronic wavefunctions energies implemented expression of macroscopic framework band without electron-hole interaction. Contributions intra-band transitions are taken into account by adding...

A systematic study of the cross sections for $K$-shell ionization by 2.0-MeV-electron impact has been made as a function atomic number. The 32 elements from V ($Z=23$) to Bi ($Z=83$) were first measured relative each other, and then normalized 43 b at Sn ($Z=50$). Thus errors usually associated with absolute measurements minimized did not obscure minor variations in $Z$ dependence sections. values drop 353 9.9 Bi. general trend data is agreement theoretical predictions Kolbenstvedt. However,...

A new method for solving the central equation of optimized effective potential is presented and applied to exchange-only, orbital-dependent energy functional. The local written as sum a Slater exchange potential, that gives exact asymptotic behaviour, plus short-range correction represented by linear combination L2-functions. easy implement, can also be efficiently molecules clusters high-quality results. Energies, eigenvalues densities obtained closed-shell atoms are compared with...

Atomistic molecular dynamics computer simulations have been performed on the columnar state of discogen hexakis(pentyloxy)triphenylene (HAT5). The parameters empirical model potential taken from AMBER and OPLS force fields. A 10 ns simulation run has carried out in Berendsen's ensemble at pressure P = 0.1 MPa temperature T 375 K to study bulk structure. structure characterized by obtaining structural that compare favorably with those deduced X-ray diffraction experiments. 13C 2H NMR data...

$K$-shell ionization cross sections have been measured at 2.04-MeV incident electron energy for 32 elements from V ($Z=23$) to Bi ($Z=83$). Measured drop a value of 353 b 9.9 Bi. The general trend the $Z$ dependence is in agreement with theoretical predictions Kolbenstvedt. However, variations by as much 30% one element next are not accounted theory.

Ab initio calculations of the full-band structure SiO/sub 2/ are worked out. Both conduction and valence bands investigated by means two different techniques: Hartree-Fock (HF) density-functional theory (DFT). A number energy-level diagrams calculated in order to compare corresponding density states a range about 10 eV. Different crystal structures studied, that known be built-up same fundamental unit, namely, 4/ tetrahedron. All analyzed systems polymorphs silica; specifically, /spl alpha/-...

An alternative method for taking into account correlation effects in the calculation of Auger decay rates is presented here. This approach, which generalizes a technique recently proposed by authors [Phys. Rev. A 39, 6247 (1989)], based on coupling final ionic states and channels has been applied to construction ``theoretical'' spectrum LiF molecule transitions also due shakeoff shakeup processes are taken account.

A posteriori corrections to the Hartree-Fock total energy of crystalline compounds are obtained with density functional proposed by Colle and Salvetti [Theor. Chem. Acta 37, 329 (1975)]. Results presented for diamond, graphite metallic lithium. For covalent systems, error on atomization is order 8%, both small large basis sets. lithium correlation more severely underestimated but can be reduced a few percent using mixed scheme, which utilizes CS within ionic sphere, Wigner or Ceperley-Alder...

A new method for calculating Auger decay rates in molecules is proposed and tested. Essential features are (1) construction of the continuum orbital via solution Lippmann-Schwinger equation with a projected potential, (2) matching asymptotic region wave function eigenfunctions long-range Hamiltonian, (3) complete evaluation matrix elements between Hartree-Fock functions initial final states. The tested on KLL spectrum atomic Ne then used to predict LiF molecule ionized its deepest shell.

Electronic and structural properties of polypyrroles oxidized by different concentrations chlorine atoms or molecules are studied with the use a density functional method implemented plane waves pseudo-potentials for core electrons. The calculated compared those obtained neutral system that in good agreement available experimental data. role counterion oxidation process is extensively shown to be crucial localization charge defects.

We present an ab initio quantum-mechanical study, based on Car-Parrinello molecular dynamics, of electronic, optical, and structural properties the three base forms polyaniline polymers. To avoid finite-size effects encountered in study oligomers, we have represented each polymer by a periodic isolated infinite chain. provided detailed information morphology chain terms bond lengths, angles, torsion twisting bending backbone, analyzing also temperature effects. From ground-state geometry...