scholarly journals THE METHOD OF INCREMENTS — A WAVEFUNCTION-BASED AB-INITIO CORRELATION METHOD FOR SOLIDS

2007 ◽  
Vol 21 (13n14) ◽  
pp. 2204-2214 ◽  
Author(s):  
BEATE PAULUS
Keyword(s):  
Experimental Data ◽  
Ab Initio ◽  
Ground State ◽  
Infinite System ◽  
Correlation Energy ◽  
Correlation Method ◽  
Many Body ◽  
Hartree Fock ◽  
The Many ◽  
Good Agreement

The method of increments is a wavefunction-based ab initio correlation method for solids, which explicitly calculates the many-body wavefunction of the system. After a Hartree-Fock treatment of the infinite system the correlation energy of the solid is expanded in terms of localised orbitals or of a group of localised orbitals. The method of increments has been applied to a great variety of materials with a band gap, but in this paper the extension to metals is described. The application to solid mercury is presented, where we achieve very good agreement of the calculated ground-state properties with the experimental data.

EFFECTS OF CORE POLARIZATION AND PAIRING CORRELATIONS ON SOME GROUND-STATE PROPERTIES OF DEFORMED ODD-MASS NUCLEI WITHIN THE HIGHER TAMM–DANCOFF APPROACH

2011 ◽  
Vol 20 (02) ◽  
pp. 252-258 ◽  
Author(s):  
LUDOVIC BONNEAU ◽  
JULIEN LE BLOAS ◽  
PHILIPPE QUENTIN ◽  
NIKOLAY MINKOV
Keyword(s):  
Ground State ◽  
Mean Field ◽  
Energy Difference ◽  
Pair Type ◽  
Many Body ◽  
Hartree Fock ◽  
Ground State Properties ◽  
Pairing Correlations ◽  
The Many ◽  
The Impact

In self-consistent mean-field approaches, the description of odd-mass nuclei requires to break the time-reversal invariance of the underlying one-body hamiltonian. This induces a polarization of the even-even core to which the odd nucleon is added. To properly describe the pairing correlations (in T = 1 and T = 0 channels) in such nuclei, we implement the particle-number conserving Higher Tamm–Dancoff approximation with a residual δ interaction in each isospin channel by restricting the many-body basis to two-particle–two–hole excitations of pair type (nn, pp and np) on top of the Hartree–Fock solution. We apply this approach to the calculation of two ground-state properties of well-deformed nuclei |Tz| = 1 nuclei around 24 Mg and 48 Cr , namely the isovector odd-even binding-energy difference and the magnetic dipole moment, focusing on the impact of pairing correlations.

Wave-number dependence of the static screening function of an interacting electron gas. I. Lowest-order Hartree–Fock corrections

1970 ◽  
Vol 48 (2) ◽  
pp. 155-165 ◽  
Author(s):  
D. J. W. Geldart ◽  
Roger Taylor
Keyword(s):  
Coulomb Interaction ◽  
Ground State ◽  
Electron Gas ◽  
Perturbation Expansion ◽  
Wave Number ◽  
Many Body ◽  
Hartree Fock ◽  
The Many ◽  
Static Screening ◽  
Zero Frequency

The lowest-order Hartree–Fock contributions to the zero frequency screening function are examined for an interacting electron gas in its ground state. Computational methods are developed to treat singularities associated with the bare coulomb interaction and vanishing energy denominators of the many-body perturbation expansion. Numerical results are given. The wave-number dependence in the intermediate (k ~ kF) range differs considerably from that of previous estimates.

Nitrosyl cyanide and related aspects of the ONCN potential surface

1978 ◽  
Vol 31 (11) ◽  
pp. 2349 ◽  
Author(s):  
BG Gowenlock ◽  
L Radom
Keyword(s):  
Experimental Data ◽  
Ab Initio ◽  
Molecular Orbital ◽  
Related Species ◽  
Potential Surface ◽  
Basis Sets ◽  
Molecular Orbital Calculations ◽  
Hartree Fock ◽  
Split Valence ◽  
Good Agreement

Ab initio molecular orbital calculations using the restricted Hartree-Fock approach have been carried out for nitrosyl cyanide and related species on the ONCN potential surface. Full geometry optimizations have been performed with the minimal STO-3G and split-valence 4-31G basis sets. Calculated (4-31G) geometries are in good agreement with available experimental data as are the energy changes in the reactions ONCN → NO + CN and NO + CN → N2 + CO. Possible mechanisms are discussed.

Correlation energy in triplet electronic states. Application of the many-body Rayleigh-Schrödinger perturbation theory in the restricted Roothaan-Hartree-Fock formalism

1981 ◽  
Vol 46 (6) ◽  
pp. 1324-1331 ◽  
Author(s):  
Petr Čársky ◽  
Ivan Hubač
Keyword(s):  
Wave Function ◽  
Perturbation Theory ◽  
Correlation Energy ◽  
Electronic States ◽  
Many Body ◽  
Third Order ◽  
Explicit Formulas ◽  
Hartree Fock ◽  
The Many ◽  
Schrödinger Perturbation

Explicit formulas over orbitals are given for the correlation energy in triplet electronic states of atoms and molecules. The formulas were obtained by means of the diagrammatic many-body Rayleigh-Schrodinger perturbation theory through third order assuming a single determinant restricted Roothaan-Hartree-Fock wave function. A numerical example is presented for the NH molecule.

scholarly journals AB INITIO STUDY ON OPTIMIZATION OF BISPHENOL A AND PHOSGENE TO MANUFACTURE POLYCARBONATE

2020 ◽  
Vol 20 (4) ◽  
pp. 995-998
Author(s):  
BAHTIYAR A. MAMEDOV ◽  
ELIF SOMUNCU ◽  
EBRU KARATAS
Keyword(s):  
Experimental Data ◽  
Bisphenol A ◽  
Ab Initio ◽  
Ground State ◽  
Optimization Method ◽  
Geometric Optimization ◽  
Basis Sets ◽  
Ab Initio Study ◽  
Hartree Fock ◽  
Design Materials

Geometric optimization is played an important to manufacture and design materials in many implementations. Therefore the choice of optimization method is of considerable significance to easily solve the problems. In this work, the ground state geometries for bisphenol A and phosgene that manufacture polycarbonate have been optimized using the Hartree-Fock method with different basis sets. The optimization results for bisphenol A and phosgene are compared with theoretical and experimental data. The obtained optimizations results have been shown that our data are in agreement with the literature and experimental data.

scholarly journals All-order calculations of the energy levels of heavy elements Indium (In) and Tin (Sn)

2019 ◽  
Vol 14 (9) ◽  
pp. 34
Author(s):  
Dinh Thi Hanh
Keyword(s):  
Energy Levels ◽  
Potential Method ◽  
Heavy Elements ◽  
Many Body ◽  
Interaction Technique ◽  
Hartree Fock ◽  
Valence Electrons ◽  
Many Body Perturbation Theory ◽  
The Many ◽  
Good Agreement

The energy levels of the heavy elements In, Sn+ and Sn are presented in this article. Dominating corrections beyond the relativistic Hartree-Fock method are included to all orders in the Coulomb interaction using the Feynman diagram technique and the correlation potential method. The configuration interaction technique is combined with the many-body perturbation theory to construct the many-electron wave function for valence electrons and to include core-valence correlations. The good agreement of the results of our calculation with experiment data illustrates the power of the method.

Calculating Fundamental Vibrational Frequencies of Rutile by Combining Ab Initio Method with GF Matrix Method

1994 ◽  
Vol 05 (02) ◽  
pp. 299-301
Author(s):  
Lin Libin ◽  
Zheng Xiangyin
Keyword(s):  
Experimental Data ◽  
Ab Initio ◽  
Matrix Method ◽  
Cluster Model ◽  
Normal Modes ◽  
Vibrational Frequencies ◽  
Ab Initio Method ◽  
Environment Factor ◽  
Factor Α ◽  
Good Agreement

Based on cluster model, we have calculated the fundamental vibrational frequencies of rutile by combining ab initio method and Wilson’s GF-matrix method. In the calculation, we have introduced the concept of environment factor α to correct the force field of the cluster model. The results of calculation are in good agreement to the experimental data and the normal modes give us clear physical picture of the crystal vibration.

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