The Rovibrational Dependence of the 14N Nuclear Quadrupole Coupling Constants in the X2Σ+ and B2Σ+ States of CN from the Multireference CI Approach

2003 ◽  
Vol 68 (3) ◽  
pp. 509-528 ◽  
Author(s):  
Rudolf Polák ◽  
Jiří Fišer
Keyword(s):  
Dipole Moments ◽  
Wave Functions ◽  
Coupling Constants ◽  
Basis Sets ◽  
Configuration Spaces ◽  
Spectroscopic Constants ◽  
Quadrupole Coupling ◽  
Correlation Consistent ◽  
Consistent Basis

In using several augmented correlation-consistent basis sets and reference configuration spaces, the 14N quadrupole coupling constants (QCCs) of rovibrational levels of the X2Σ+ and B2Σ+ states of the CN radical are computed from internally contracted multireference configuration interaction wave functions. To examine the overall quality of the correlated wave functions used for computing the expectation values of the electric field gradient (EFG) tensor at the N nucleus, electric dipole moments are calculated and spectroscopic constants are derived from corresponding potential energy curves. The adequacy of the expectation value approach to the evaluation of the EFG and dipole moment is discussed. The calculated vibrational dependence of the 14N QCC compares reasonably with the available experimental data.

scholarly journals Spectroscopic constants and anharmonic force field of dithioformic acid and its isomers: a theoretical study

2021 ◽  
Author(s):  
Weixiu Pang ◽  
Xiaomin Song ◽  
Yunbin Sun ◽  
Meishan Wang
Keyword(s):  
Force Field ◽  
Dipole Moments ◽  
Molecular Structures ◽  
Basis Sets ◽  
Astronomical Observation ◽  
Spectroscopic Constants ◽  
Fundamental Frequencies ◽  
Correlation Consistent ◽  
Consistent Basis ◽  
Anharmonic Force

Abstract The potential astronomical interest dithioformic acid (trans-HC(=S)SH) exists five isomers and has received considerable attention of astronomical observation in recent years. The different positions of H atoms of five isomers lead to diverse point groups, dipole moments, and spectroscopic constants. The anharmonic force field and spectroscopic constants of them are calculated using CCSD(T) and B3LYP employing correlation consistent basis sets. Molecular structures, dipole moments, rotational constants, and fundamental frequencies of trans-HC(=S)SH are compared with the available experimental data. The B3LYP/Gen=5 and CCSD(T)/Gen=Q results can reproduce them well. Molecular structures, dipole moments, relative energies, spectroscopic constants of cis-HC(=S)SH and dithiohydroxy carbene (DTHC) are also calculated. The new data obtained in this study are expected to guide the future high resolution experimental work and to assist astronomical search for CH2S2.

Electron Affinities of BN, NO and NF: Coupled Cluster and Multireference Configuration Interaction Calculations

2005 ◽  
Vol 70 (7) ◽  
pp. 923-940 ◽  
Author(s):  
Jiří Fišer ◽  
Rudolf Polák
Keyword(s):  
Configuration Interaction ◽  
Relativistic Effects ◽  
Basis Set ◽  
Basis Sets ◽  
Spectroscopic Constants ◽  
Coupled Cluster ◽  
Electron Affinities ◽  
Complete Basis Set ◽  
Correlation Consistent ◽  
Consistent Basis

The accurate adiabatic electron affinities (EA) of the BN, NO and NF molecules have been determined using the coupled cluster approach and multireference configuration interaction methods. By combining large doubly augmented correlation-consistent basis sets (through the sextuple zeta) and complete basis set extrapolations with corrections for core-valence correlation and relativistic effects, we find that the RCCSD(T) method gives EA(BN) = 3.153 eV in very close agreement with experiment and predicts EA(NF) = 0.247 eV. The RCCSD(T) and UCCSD(T) EA(NO) results, 0.008 and 0.031 eV, bracket the experimental value. For both the neutral and anionic ground state species the usual spectroscopic constants were derived.

scholarly journals Analysis of the Quadrupole Coupling Constants and Mössbauer Iso- meric Shifts in Halogen Compounds Within the Gaussian98 Code

2000 ◽  
Vol 55 (1-2) ◽  
pp. 271-275
Author(s):  
O. Kh. Poleshchuk ◽  
J. N. Latosińska ◽  
B. Nogaj
Keyword(s):  
Experimental Data ◽  
Halogen Bond ◽  
Dipole Moments ◽  
Energy Levels ◽  
Point Of View ◽  
Coupling Constants ◽  
Good Test ◽  
Quadrupole Coupling ◽  
Bonding Properties

A comparison of the experimental and calculated nuclear quadrupole coupling constants of diatomic halogen, interhalogen, trihalide ions and complexes of pyridine is a good test of reliability of semiempirical and non-empirical theories as well as their usefulness in the interpretation of quadrupole coupling data from the qualitative and quantitative point of view. Therefore, a practical way of gaining insight into the bonding properties and electronic structure of such systems consists of combining semiempirical MO calculations with experimental data to derive reliable information. In the present work we report the results of ab initio studies of several iodine containing molecules and ions using the calculated NQCC as a test of the quality of the wavefunctions. To demonstrate the quality of our calculations, we compare the calculated halogen-halogen bond length and QCC with the corresponding experimental values for the compounds studied. With a few exceptions, the overall agreement with experiment is most satisfactory. The results on dipole moments and energy levels are also in a good agreement with the experimental data, however these quantities were measured only in the few cases.

Theoretical study with rovibrational and electronic transitionmoment calculation of the ion LiCs+

2006 ◽  
Vol 84 (11) ◽  
pp. 959-971 ◽  
Author(s):  
M Korek ◽  
A M Moghrabi ◽  
A R Allouche ◽  
M Aubert Frécon
Keyword(s):  
Internuclear Distance ◽  
Bound States ◽  
Dipole Moments ◽  
Basis Sets ◽  
Spectroscopic Constants ◽  
Gaussian Basis Sets ◽  
Transition Dipole ◽  
Vibrational Levels ◽  
Moment Functions ◽  
Dependent Polarization

For the molecular ion LiCs+ the potential energy are calculated for the 39 lowest molecular states of symmetries 2Σ+, 2Π, 2Δ, and Ω = 1/2, 3/2, 5/2. Using an ab initio method, the calculation is based on nonempirical pseudopotentials and parameterized [Formula: see text]-dependent polarization potentials. Gaussian basis sets are used for both atoms and spin-orbit effects are taken into account. The spectroscopic constants for 20 states are calculated by fitting the calculated energy values to a polynomial in terms of the internuclear distance r. Through the canonical functions approach, the eigenvalue Ev, the abscissas of the corresponding turning points (rmin and rmax), and the rotational constants Bv are calculated for up to 44 vibrational levels for four bound states. Using the same approach the dipole moment functions, the corresponding matrix elements, and the transition dipole moments are calculated for the bound states (1)2Σ+, (2)2Σ+, and (1)2Π. The comparison of the present results with those available in literature for the ground state shows a very good agreement. Extensive tables of energy values versus internuclear distance are displayed at the following address: http://lasim.univ-lyon1.fr/allouche/licsso.html.PACS Nos.: 31.15.Ar, 31.25.–v, 31.25.Nj

Density Functional Theory Studies of Bonding in Complexes H3N···XY of Ammonia and Dihalogen Molecules: A Comparison with Experimental Results from Rotational Spectroscopy

2002 ◽  
Vol 57 (6-7) ◽  
pp. 537-543 ◽  
Author(s):  
O. Kh. Poleshchuk ◽  
A. C. Legona
Keyword(s):  
Density Functional ◽  
Natural Bond Orbital ◽  
Coupling Constants ◽  
Rotational Spectroscopy ◽  
Charge Redistribution ◽  
Functional Theory ◽  
Quadrupole Coupling ◽  
Nuclear Quadrupole ◽  
Experimental Values

The electron density and nuclear quadrupole coupling constants (NQCC) of the H3N...XY (n a type in Mulliken notation) complexes, (X, Y = F, Cl, Br and I), are analyzed with the aid of density functional calculations. To demonstrate the quality of the calculations, various bond lengths and NQCCs obtained by using the hybrid Becke-Lee-Perdew-Yang functional are compared with the corresponding experimental values determined from rotational spectroscopy. An analysis of the NQCC values and various quantities derived fromthe natural bond orbital approach reveals that the molecular interaction is mainly electrostatic, with probably only a small extent of intermolecular electric charge redistribution on complex formation

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