Similarity of MEP distributions obtained using several semiempirical and ab initio wave functions: A cluster analysis

1993 ◽  
pp. 339-340
Author(s):  
J. Rodríguez ◽  
F. Manaut ◽  
F. Sanz
Keyword(s):  
Cluster Analysis ◽  
Ab Initio ◽  
Wave Functions

An ab initio MO study of conformation structure of nicotinamide and its derivatives

1983 ◽  
Vol 48 (7) ◽  
pp. 1842-1853 ◽  
Author(s):  
Stanislav Böhm ◽  
Josef Kuthan
Keyword(s):  
Ab Initio ◽  
Wave Functions ◽  
Semiempirical Calculations ◽  
Rigid Rotor ◽  
Qualitative Similarity ◽  
Ab Initio Mo ◽  
Experimental Findings

Conformation of nicotinamide (I), 3-carbamoylpyridinium (IIa), 1-methyl-3-carbamoylpyridinium (IIb), and 1-methyl-1,4-dihydronicotinamide (IIIa) has been studied in the rigid rotor approximation on the basis of non-empirical STO-3G wave functions. The rotation barriers decrease in the order: IIIa > I ~ IIb > IIa. When confronted with semiempirical calculations, the conformation curves of molecular energy show a better qualitative similarity to the EHT than to NDDO and particularly to CNDO/2 curves. Relation of the calculated characteristics to experimental findings is discussed.

scholarly journals Multifractality of ab initio wave functions in doped semiconductors

2019 ◽  
Vol 111 ◽  
pp. 141-147 ◽  
Author(s):  
Edoardo G. Carnio ◽  
Nicholas D.M. Hine ◽  
Rudolf A. Römer
Keyword(s):  
Ab Initio ◽  
Wave Functions ◽  
Doped Semiconductors

Spectroscopic constants for tritiated and deuterated

1984 ◽  
Vol 62 (12) ◽  
pp. 1871-1874 ◽  
Author(s):  
Grady D. Carney
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Ab Initio ◽  
Energy Surface ◽  
Zero Point ◽  
Wave Functions ◽  
Spectroscopic Constants ◽  
Vibration Rotation

Theoretical vibration–rotation coefficients for tritiated and deuterated [Formula: see text] are reported for Carney and Porter's ab initio electronic CI potential energy surface. In the calculation of coefficients connecting the zero-point and fundamental states of vibration, accurate vibrational CI wave functions, consisting of 220 configuration functions, were used.

Ab Initio Calculations of Vibrational Energy Levels and Transition Dipole Moments of CO2 Molecules

2008 ◽  
Author(s):  
Zhi Liang ◽  
Hai-Lung Tsai
Keyword(s):  
Ab Initio ◽  
Vibrational Energy ◽  
Molecular Spectroscopy ◽  
Dipole Moments ◽  
Energy Levels ◽  
Wave Functions ◽  
Molecular Vibration ◽  
Transition Dipole ◽  
Transition Dipole Moments ◽  
Vibrational Energy Levels

Ab initio MD simulation of laser-matter interactions is a hot area in the study of the mechanisms of photo-dissociation, photo-ionization and laser induced chemical reactions. The major problems in the study of laser-molecule interactions are to determine the energies and wave functions of molecular vibration states and the molecular transition dipole moments. An efficient method is presented to calculate the intramolecular potential energies and electrical dipole moments of CO2 molecules at the electronic ground state by solving the Kohn-Sham (KS) equation for a total of 101,992 nuclear configurations. The Projector-Augmented Wave (PAW) exchange-correlation potential functionals and Plane Wave (PW) basis functions were used in solving the KS equation. The calculated intra-molecular potential function was then included in the pure vibrational Schro¨dinger equation to determine the vibrational energy eigen values and eigen functions. The vibrational wave functions combined with the calculated dipole moment function were used to determine the transition dipole moments. The calculated results have a good agreement with experimental values. These results can be further used to determinations of molecular spectroscopy and laser absorption coefficients.

Valence-bond studies of 4-electron 3-centre bonding units. I. The π-electrons of O3, NO2−, and CH2N2

1978 ◽  
Vol 56 (8) ◽  
pp. 1093-1101 ◽  
Author(s):  
Richard D. Harcourt ◽  
Walter Roso
Keyword(s):  
Electronic Structure ◽  
Ab Initio ◽  
Valence Bond ◽  
Ground States ◽  
Wave Functions ◽  
Dipolar Cycloaddition ◽  
Cycloaddition Reactions ◽  
Electronic Mechanism ◽  
Increased Valence

Some ab-initio valence-bond wave-functions are reported for the π-electrons of the ground-states of O3, NO2−, and CH2N2. Examination of these wave-functions provides further support for the hypothesis that, for the ground-states of many electron-excess molecules, important valence-bond structures are those that are compatible with the electroneutrality principle, i.e. they carry either small or zero formal charges on each of the atoms. For O3 and CH2N2, the important valence-bond structures with zero atomic formal charges are [Formula: see text]Each of these structures has a 'long-bond' between non-adjacent atoms. The significance of 'long-bond' (or spin-paired diradical) structures for the electronic mechanism of 1,3-dipolar cycloaddition reactions is discussed and 'increased-valence' descriptions of the electronic structure of each molecule are presented. Some comments on the utility of 'increased-valence' structures are provided.

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