Ab initio anharmonic force field and equilibrium structure of vinyl bromide

Ab initio anharmonic force field and equilibrium structure of vinyl fluoride and vinyl iodide

“…The agreement between the calculated and the experimental vibrational frequencies m i is rather good, the median of absolute deviations being only 13 cm À1 (1%). This is comparable to or even slightly better than the results found for vinyl chloride [1] and vinyl bromide [2]. Likewise, the deviations are mainly systematic and the largest ones are for the CH bond stretchs.…”

“…The accurate equilibrium structures of vinyl chloride [1] and vinyl bromide [2] have been recently determined using three different methods: r m mass-dependent method [3], semi-experimental method (where the equilibrium rotational constants are obtained by correcting the experimental ground state rotational constants with the ab initio vibration-rotation interaction constants (a-constants)) [4,5] and the ab initio method. These three methods gave results in good agreement indicating that the derived structures are really accurate.…”

Ab initio anharmonic force field and equilibrium structure of propene

“…On the other hand, it is a large amplitude motion and this could severely affect the accuracy of the calculated anharmonic force field. The agreement is comparable or better than that found for other molecules without large amplitude motion as vinyl halides [37,39,40]. Thus, it may be concluded that, in the particular case of propene, the torsion behaves as a small-amplitude vibration.…”

Microwave spectrum and structure of furfural

“…This might be the case for furfural which is rather heavy and has a low torsion frequency for the HCO group, namely, 127 cm À1 for cis and 146 cm À1 for trans [11]. Demaison, Rudolph and co-workers [30][31][32][33][34] applied the mass-dependent (r m ) method of Watson et al [35] to a variety of molecules (diatomic, linear, symmetric top Table 5 Rotational parameters of 13 C substituted furfural species Parameter [18]) and apply to the last digits shown. b Number of rotational transitions fit for each isotopolog.…”