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.

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.

AB INITIO STUDY OF SPECTROSCOPIC CONSTANTS AND ANHARMONIC FORCE FIELD OF AsH2 RADICAL

2011 ◽  
Vol 10 (06) ◽  
pp. 849-860 ◽  
Author(s):  
YURONG GUO ◽  
MEISHAN WANG ◽  
CHUANLU YANG ◽  
YUTING SUN ◽  
ZILIANG ZHU
Keyword(s):  
Force Field ◽  
Experimental Studies ◽  
Dft Method ◽  
Equilibrium Structure ◽  
Vibrational Frequencies ◽  
Force Constants ◽  
Basis Sets ◽  
Spectroscopic Constants ◽  
Rotational Constants ◽  
Anharmonic Force

The equilibrium structure, spectroscopic constants and anharmonic force field of AsH2 have been investigated at B3LYP, B3PW91 and MP2 methods employing the basis sets of cc-pVNZ and aug-cc-pVNZ (N ∈ { T , Q }), respectively. The computed geometries, rotational constants, part of vibrational frequencies, quartic and sextic centrifugal distortion constants are compared with the available experimental data or theoretical results. The other vibrational frequencies, equilibrium rotational constants, anharmonic constants, vibration–rotation interaction constants, cubic and quartic force constants of AsH2 are also predicted for the first time. Furthermore, the calculated results show that the DFT method is superior to MP2 at the calculations of geometries, spectroscopic constants and force constants. The B3PW91/aug-cc-pVQZ results are more reliable. Our predictions can provide useful data for the experimental studies of the corresponding spectroscopic constants of AsH2 .

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.

DENSITY FUNCTIONAL THEORY STUDIES OF SPECTROSCOPIC CONSTANTS AND ANHARMONIC FORCE FIELD OF O35ClO

2013 ◽  
Vol 12 (02) ◽  
pp. 1250117 ◽  
Author(s):  
ZILIANG ZHU ◽  
MEISHAN WANG ◽  
CHUANLU YANG ◽  
MEIZHONG MA ◽  
WENWANG LIU
Keyword(s):  
Force Field ◽  
Density Functional ◽  
Equilibrium Structure ◽  
Substantial Improvement ◽  
Basis Sets ◽  
Spectroscopic Constants ◽  
Functional Theory ◽  
Vibration Rotation ◽  
Centrifugal Distortion Constants ◽  
Anharmonic Force

The equilibrium structure, spectroscopy constants and anharmonic force field of O35ClO have been calculated at B3PW91 and B3LYP levels of theory with two basis sets 6-311++G(2df,2pd) and 6-311++G(3df,3pd) , respectively. The computed geometries, dipole moment, rotational constants, vibration–rotation interaction constants, vibrational band origins, anharmonic constants, quartic, and sextic centrifugal distortion constants are compared with the available experimental data. The cubic and quartic force constants are predicted. The calculated results show that the B3PW91 results are in excellent agreement with experiment and represent a substantial improvement over the results obtained from B3LYP.

Theoretical study of spectroscopic constants and anharmonic force field of formaldehyde

2014 ◽  
Vol 13 (06) ◽  
pp. 1450049 ◽  
Author(s):  
Xuejun Wang ◽  
Meishan Wang ◽  
Chuanlu Yang ◽  
Jing Li ◽  
Dianmin Tong
Keyword(s):  
Force Field ◽  
Theoretical Data ◽  
Dft Method ◽  
Force Constants ◽  
Coupling Constants ◽  
Basis Set ◽  
Basis Sets ◽  
Spectroscopic Constants ◽  
Equilibrium Geometries ◽  
Anharmonic Force

The equilibrium geometries of formaldehyde are optimized with B3LYP, B3PW91 and MP2 methods employing three basis sets 6-311++G(2d,2p), aug-cc-pVTZ and cc-pVTZ, respectively, which agree well with the corresponding experimental and previous theoretical data. The best optimized geometries are obtained at the theoretical level B3LYP/6-311++G(2d,2p) basis set. Basing on the calculated equilibrium geometries, the spectroscopic constants and anharmonic force field of H 2 CO are investigated. The results show that DFT method is superior to MP2 method at the calculation of spectroscopic constants and force constants of H 2 CO . The vibration–rotation interaction constants and fundamental vibrational wave numbers of H 2 CO are firstly theoretically calculated. The Coriolis coupling constants, cubic force constants and most of quartic force constants are firstly theoretically predicted.

DFT anharmonic force field, and spectroscopic constants for phosphaethene, CH2PH

2017 ◽  
Vol 16 (3) ◽  
pp. 207-216 ◽  
Author(s):  
Wei-Xiu Pang ◽  
Hong-Ye Wu ◽  
Jian-Jun Zhao ◽  
Yi Lu ◽  
Yun-Bin Sun
Keyword(s):  
Force Field ◽  
Spectroscopic Constants ◽  
Anharmonic Force

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

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