Large amplitude vibrations of acetyl isocyanate, methyl cyanoformate, and acetyl cyanate

2019 ◽  
Vol 21 (7) ◽  
pp. 3597-3605 ◽  
Author(s):  
Samira Dalbouha ◽  
María L. Senent
Keyword(s):  
Ab Initio ◽  
Empirical Formula ◽  
Large Amplitude ◽  
Far Infrared ◽  
Infrared Region ◽  
Coupled Cluster ◽  
Variational Procedure ◽  
Explicitly Correlated ◽  
Large Amplitude Motions ◽  
Large Amplitude Vibrations

The far infrared region of three detectable molecules sharing the empirical formula C3H3O2N, acetyl isocyanate CH3CONCO (AISO), methyl cyanoformate NC–COOCH3 (MCN) and acetyl cyanate CH3COOCN (ACN), is explored using explicitly correlated coupled cluster ab initio methods and a variational procedure designed for non-rigid species and large amplitude motions.

scholarly journals Ab Initio Study of the Large Amplitude Motions of Various Monosubstituted Isotopologues of Methylamine (CH3-NH2)

2021 ◽  
Vol 9 ◽  
Author(s):  
Muneerah Mogren Al-Mogren ◽  
María Luisa Senent
Keyword(s):  
Large Amplitude ◽  
Vibrational Energy ◽  
Energy Levels ◽  
Three Dimensional ◽  
Far Infrared ◽  
Infrared Region ◽  
Strong Interactions ◽  
Three Dimensional Model ◽  
Large Amplitude Motions ◽  
Centrifugal Distortion Constants

CCSD(T)-F12 theory is applied to determine electronic ground state spectroscopic parameters of various isotopologues of methylamine (CH3-NH2) containing cosmological abundant elements, such as D, 13C and 15N. Special attention is given to the far infrared region. The studied isotopologues can be classified in the G12, G6 and G4 molecular symmetry groups. The rotational and centrifugal distortion constants and the anharmonic fundamentals are determined using second order perturbation theory. Fermi displacements of the vibrational bands are predicted. The low vibrational energy levels corresponding to the large amplitude motions are determine variationally using a flexible three-dimensional model depending on the NH2 bending and wagging and the CH3 torsional coordinates. The model has been defined assuming that, in the amine group, the bending and the wagging modes interact strongly. The vibrational levels split into six components corresponding to the six minima of the potential energy surface. The accuracy of the kinetic energy parameters has an important effect on the energies. Strong interactions among the large amplitude motions are observed. Isotopic effects are relevant for the deuterated species.

Microwave spectrum, large‐amplitude motions, and ab initio calculations for N2O5

1996 ◽  
Vol 105 (17) ◽  
pp. 7249-7262 ◽  
Author(s):  
J.‐U. Grabow ◽  
A. M. Andrews ◽  
G. T. Fraser ◽  
K. K. Irikura ◽  
R. D. Suenram ◽  
...  
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Large Amplitude ◽  
Microwave Spectrum ◽  
Large Amplitude Motions

scholarly journals Ab initio description of large amplitude motions in solid N2. III. Libron–phonon coupling

1984 ◽  
Vol 81 (9) ◽  
pp. 4118-4126 ◽  
Author(s):  
W. J. Briels ◽  
A. P. J. Jansen ◽  
Ad van der Avoird
Keyword(s):  
Ab Initio ◽  
Large Amplitude ◽  
Phonon Coupling ◽  
Large Amplitude Motions ◽  
Solid N2
Sign in / Sign up

Export Citation Format

Share Document