A quantum approach to the mechanism of electrochemical reductions

1986 ◽  
Vol 64 (12) ◽  
pp. 2359-2364 ◽  
Author(s):  
Juan J. Novoa
Keyword(s):  
Total Energy ◽  
Electrochemical Reduction ◽  
Second Order ◽  
Basis Sets ◽  
Hartree Fock ◽  
Quantum Approach ◽  
Moller Plesset

Using the Hartree–Fock method and, in some cases, the second order Moller–Plesset perturbational method, with 4-31G, 4-31 + G, and 4-31 + G* basis sets, a first approach to the study of the mechanism of electrochemical reduction from formaldehyde to ethanol is presented. The total energy and optimized geometry of each of the molecules involved are also given. A proton–electron–proton–electron type mechanism is proposed.

scholarly journals AB INITIO STUDY OF AMMONIA CLUSTERS: (NH3)n (n = 2-6)

2010 ◽  
Vol 8 (3) ◽  
pp. 392-396 ◽  
Author(s):  
Herudi Kandau ◽  
Hanggara Sudrajat ◽  
Andreas Napitupulu ◽  
Syahrul Khairi ◽  
Zaky Al-Fatony ◽  
...  
Keyword(s):  
Perturbation Theory ◽  
Ab Initio ◽  
Ab Initio Calculation ◽  
Dipole Moments ◽  
Second Order ◽  
Basis Sets ◽  
Hartree Fock ◽  
Moller Plesset ◽  
Ammonia Clusters ◽  
Hydrogen Bonded

Hydrogen bonded neutral clusters of ammonia, (NH3)n (n = 2-6), have been theoretically investigated employing the D95++(d,p) (and wherever necessary, higher) basis sets at the Hartree-Fock (HF) level as well as with second-order Møller-Plesset (MP2) perturbation theory. While the ammonia trimer and tetramer exhibit perfect molecular symmetries and are nonpolar, the pentamer and hexamer both optimize with slight deviations from perfect symmetries and are seen to posses marginal, but nonzero dipole moments. The (NH3)n linear clusters are seen to be chemically softer than the corresponding cyclic ones.   Keywords: ab initio calculation, ammonia clusters, Hartree-Fock, Møller-Plesset

CALCULATIONS WITH CORRELATED MOLECULAR WAVE FUNCTIONS: HF, MP2 AND DFT CALCULATIONS ON SECOND-ROW DIATOMIC HYDRIDES

2006 ◽  
Vol 05 (02) ◽  
pp. 223-233 ◽  
Author(s):  
F. E. JORGE ◽  
L. M. BERNARDO ◽  
E. P. MUNIZ
Keyword(s):  
Density Functional ◽  
Correlation Energy ◽  
Second Order ◽  
Wave Functions ◽  
Basis Sets ◽  
Hartree Fock ◽  
Double Zeta ◽  
Polarization Functions ◽  
Moller Plesset ◽  
Electronic Ground

The performance of the previously proposed double zeta valence quality plus polarization functions (DZP) and augmented DZP (ADZP) basis sets is tested at the Hartree–Fock, second-order Møller–Plesset, and density functional levels of theory for the electronic ground state of the second-row diatomic hydrides. Total energy, second-order correlation energy, dissociation energy, bond length, vibrational frequency, and dipole moment are calculated and compared with results obtained with popular basis sets reported in the literature. It is shown that the DZP and ADZP basis sets in general provides better accuracy for a similar number of basis functions.

Static- and frequency-dependent NLO properties of dithienothiophene and thienothiophene bridges — A computational investigation

2020 ◽  
Vol 19 (05) ◽  
pp. 2050018
Author(s):  
Sagar B. Yadav ◽  
Nagaiyan Sekar
Keyword(s):  
Density Functional ◽  
Nonlinear Optical ◽  
Chemical Reactivity ◽  
Second Order ◽  
Basis Sets ◽  
Frequency Dependent ◽  
Nlo Properties ◽  
Reactivity Descriptors ◽  
Hartree Fock ◽  
Perturbation Potential

We have explored detailed linear and nonlinear optical properties of push-pull systems bearing thienothiophene and dithienothiophene spacers. By using density functional theory (DFT), frequency-dependent strategies were applied to examine the polarizability ([Formula: see text] and hyperpolarizability ([Formula: see text] and [Formula: see text]. The set of global and range-separated hybrid functionals with different Hartree–Fock (HF) exchange percentage at two basis sets cc-pVDZ and cc-pVTZ were used to evaluate the nonlinear optical (NLO) properties. The observed trends in the absorption maxima supported by perturbation potential analysis; as the absorption maxima increases, the respective amplitude potential decreases. For the investigated compounds, [Formula: see text]-conjugation along with the type of substituted acceptor plays a crucial role in the enhancement of NLO properties. The presence of acceptor group and length of conjugation increase between the D and A group; the first- and second-order intrinsic hyperpolarizability increases, leads to enhanced first- as well as second-order hyperpolarizability. Bond length alternation (BLA)/bond order alteration (BOA) exploration suggested that compounds attain cyanine limit. The trends in NLO properties for investigated compounds are supported by chemical reactivity descriptors, hardness and hyperhardness analysis. The polarizability is linearly correlated with the hyperpolarizability parameters ([Formula: see text] and [Formula: see text] and shows a good regression coefficient by figures of merit analysis.

scholarly journals Quantum Mechanical Study of YTiO3 to the Investigation of Piezoelectricity

2011 ◽  
Vol 2011 ◽  
pp. 1-5
Author(s):  
Raimundo Dirceu de Paula Ferreira ◽  
Marcos Antonio Barros dos Santos ◽  
Maycon da Silva Lobato ◽  
Jardel Pinto Barbosa ◽  
Marcio de Souza Farias ◽  
...  
Keyword(s):  
Total Energy ◽  
Piezoelectric Properties ◽  
Piezoelectric Effect ◽  
Basis Set ◽  
Basis Sets ◽  
Gaussian Basis Sets ◽  
Hartree Fock ◽  
Generator Coordinate ◽  
Mechanical Study ◽  
Quantum Mechanical Study

In previous articles we reported through theoretical studies the piezoelectric effect in BaTiO3, SmTiO3, and YFeO3. In this paper, we used the Douglas-Kroll-Hess (DKH) second-order scalar relativistic method to investigate the piezoelectricity in YTiO3. In the calculations we used the [6s4p] and [10s5p4d] Gaussian basis sets for the O (3P) and Ti (5S) atoms, respectively, from the literature in combination with the (30s21p16d)/[15s9p6d] basis set for the Y (3D) atom, obtained by generator coordinate Hartree-Fock (GCHF) method, and they had their quality evaluated using calculations of total energy and orbital energies (HOMO and HOMO-1) of the 2TiO+1 and 1YO+1 fragments. The dipole moment, the total energy, and the total atomic charges in YTiO3 in Cs space group were calculated. When we analyze those properties we verify that it is reasonable to believe that YTiO3 does not present piezoelectric properties.

Second-order Møller–Plesset calculations with dual basis sets

2003 ◽  
Vol 118 (21) ◽  
pp. 9497-9503 ◽  
Author(s):  
Krzysztof Wolinski ◽  
Peter Pulay
Keyword(s):  
Second Order ◽  
Basis Sets ◽  
Dual Basis ◽  
Moller Plesset
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