scholarly journals Theoretical Study on the Static (Hyper)Polarizabilities of α-t-Bu-ω-CN-Poly(methylphenyl)silane

2013 ◽  
Vol 2013 ◽  
pp. 1-8
Author(s):  
Jing Li ◽  
Liang Peng ◽  
Feng Long Gu
Keyword(s):  
Electron Correlation ◽  
Conjugated Polymer ◽  
Main Chain ◽  
Theoretical Study ◽  
Correlation Effect ◽  
Basis Set ◽  
Electron Correlation Effect ◽  
Hartree Fock ◽  
Linear And Nonlinear ◽  
Good Agreement

The static linear and nonlinear optical properties of the σ-conjugated polymer α-t-Bu-ω-CN-poly(methylphenyl)silane (PMS) are studied at the Coupled-Perturbed Hartree-Fock (CPHF) level with 6-31+G(d) basis set. The calculated results reveal that the static first hyperpolarizabilities of this system increase with the main chain length and have a good agreement with experiments. The (hyper)polarizabilities per unit cell have been extrapolated to infinite chain limit and a comparison is made to those of polysilane and polyacetylene (PA). Besides, other structural properties depending on the σ-conjugated Si–Si skeleton length are investigated as well. Electron correlation effect is estimated and it turns out that the MP2 static first hyperpolarizability is about times larger than the corresponding CPHF value for the polymer with .

scholarly journals A study of Fermi hole and partial Fermi hole for Li- and C-Atoms in different states 1s 2p, 1s 3p, 1s 3d and 2s 2p

2019 ◽  
Vol 13 (27) ◽  
pp. 115-126
Author(s):  
Naeemah Ch. M.
Keyword(s):  
Physical Properties ◽  
Excited States ◽  
Electron Correlation ◽  
Correlation Effect ◽  
Position Space ◽  
Electron Correlation Effect ◽  
Hartree Fock ◽  
Fermi Hole

The electron correlation effect for inter-shell have been analysed in terms of Fermi hole and partial Fermi hole for Li-atom in the excited states (1s2 3p) and (1s2 3d) using Hartree-Fock approximation (HF). Fermi hole Δf(r12) and partial Fermi hole Δg(r12 ,r1) were determined in position space. Each plot of the physical properties in this work is normalized to unity. The calculation was performed using Mathcad 14 program.

Ab initio calculation of [OH−;e+] system with consideration of electron correlation effect

1994 ◽  
Vol 101 (7) ◽  
pp. 5925-5928 ◽  
Author(s):  
Masanori Tachikawa ◽  
Hiroshi Sainowo ◽  
Kaoru Iguchi ◽  
Kazunari Suzuki
Keyword(s):  
Ab Initio ◽  
Electron Correlation ◽  
Ab Initio Calculation ◽  
Correlation Effect ◽  
Electron Correlation Effect

Conformational Structure of Chloromethyldichlorophosphines

2002 ◽  
Vol 57 (6-7) ◽  
pp. 333-336
Author(s):  
Evgenii A. Romanenko ◽  
Alexander M. Nesterenko
Keyword(s):  
Experimental Data ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Electron Correlation ◽  
Basis Set ◽  
Conformational Structure ◽  
Gauche Conformation ◽  
Nuclear Quadrupole ◽  
Set Up ◽  
Good Agreement

IThe 35Cl nuclear quadrupole resonances (77 K) and ab initio calculations of trichloromethyldichlorophosphine () show that it exists in the chess conformation form. The barrier to internal rotation about the P-C bond in I at the RHF/6-31++ G(d,p) level equals to 38.1 kJ mol-1. In chloromethyldichlorophosphine (II) the extension of the basis set up to the RHF/6-311++G(df, pd) level does not improve the description of the most preferable gauche-conformation; only if electron correlation (at the MP2 level) is taken into account the results are in a good agreement with experimental data.

Calculations of Perovskite Surface Relaxation

2000 ◽  
Vol 654 ◽  
Author(s):  
E. Heifets ◽  
E.A. Kotominc ◽  
R.I. Eglitisc ◽  
R.E. Cohen
Keyword(s):  
Thin Films ◽  
Surface Energy ◽  
Ab Initio ◽  
Shell Model ◽  
Electron Correlation ◽  
Surface Relaxation ◽  
Hartree Fock ◽  
Semi Empirical ◽  
Good Agreement ◽  
Correlation Corrections

AbstractThe (100) and (110) surface relaxations are calculated for SrTiO3 and BaTiO3 perovskite thin films by means of a semi-empirical shell model (SM) for different surface terminations. Our SM results for the (100) surface structure are in good agreement with our present ab initio Hartree-Fock calculations with electron correlation corrections, previous ab initio pseudopotential calculationsand LEED experiments. The surface energy for the Ba-, Sr-, TiO- terminated (110) surfaces is found much larger than that for the (100) one. In contrast, the surface energy for the asymmetric O-termination, where outermost O atoms are strongly on-plane displaced, is the lowest for all (110) terminations and thus the most stable.

scholarly journals Theoretical Atomic Radii of Elements (H-Cm): A Non-Relativistic Study with Gaussian Basis Set Using HF, Post-HF and DFT Methods

2021 ◽  
Author(s):  
Krishnamohan Prasanna ◽  
Sooraj Sunil ◽  
Ajith Kumar ◽  
Jamesh Joseph
Keyword(s):  
Electron Correlation ◽  
Van Der Waals ◽  
Basis Set ◽  
Dft Methods ◽  
Ionization Energies ◽  
Spin Polarized ◽  
Gaussian Basis Set ◽  
Van Der Waals Radii ◽  
Atomic Radii ◽  
Good Agreement

<div><p>We calculated the most probable radius of an atom for elements from H to Cm. The calculations were carried out by using non-relativistic, spin polarized, HF, MP2 and DFT methods with all electron Gaussian basis set<i>. </i>Periodicity of atomic radii was correlated with the experimental first ionization energies. This non-relativistic atomic radii were also compared with other theoretical atomic radii. With respect to the Dirac-Slater data, our values were in good agreement with the elements up to Sn. Relationship with van der Waals radii of noble gases was discussed. Anomalous properties of Gd and Pd were examined. Linearity of lanthanide contraction of elements with <i>4f </i>electrons is illustrated. This linearity is found independent of the extent of electron correlation. S.I. give data of calculated radii and other correlated studies (with ionization energies, another theoretical radii etc.)</p></div>

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