Theoretical study of generalized oscillator strengths for the low-lying electronic excitations of CH3Cl and CF3Cl

We report a theoretical study of electronic excitation in CH3Cl and CF3Cl by electron impact. Momentum-transfer-dependent generalized oscillator strengths (GOSs) are calculated for transitions to low-lying excited singlet-states at the equation-of-motion coupled-cluster singles and doubles level. The influence of molecular vibration is taken into account in the calculation. The theoretical results show reasonable overall agreement with experimental data reported in the literature. The shapes of the GOS profiles reveal that the 1 1E state of CH3Cl has a valence-Rydberg mixed nature, while that of CF3Cl is of a predominant C-Cl antibonding character. A comparison with the experimental GOSs of CH3Cl provides unambiguous evidence that the 3pe state is lower in energy than the 3pa1 state. Optical oscillator strengths are also calculated and comparison is made with available experimental and other theoretical results.

Generalized oscillator model for nonlinear vibration analysis using quasi-static cubication method

A generalized oscillator model for nonlinear vibration analysis of various mechanical systems was proposed and solved using the quasi-static cubication method. The proposed generalized oscillator model is useful for introducing and discussing the nonlinear vibration models of several oscillatory systems. To establish the accuracy of the quasi-static cubication method for the generalized oscillator model, a number of simulations were carried out for the nonlinear vibration models of common mechanical systems derived from the generalized oscillator model. The results obtained were found to be in good agreement with exact solutions and other approximate solutions found in the literature. Furthermore, the quasi-static cubication method was found to be accurate for a wide range of oscillation amplitudes. A significant feature of the quasi-static cubication method is its simplicity and accuracy; hence, it is considered an efficient technique for nonlinear vibration analysis in undergraduate and post-graduate courses on dynamics.