The anharmonic force fields and spectroscopic constants of electronic ground state ($\widetilde{X}^1$A') of diazirinone $({\rm N}_2{\rm CO})$ has been investigated employing the DFT (B3LYP, B3PW91, and B3P86) and MP2 methods with the cc-pVnZ (n = D, T, Q) basis sets. The calculated equilibrium geometries, ground state rotational constants, fundamental vibrational frequencies, and equilibrium quartic centrifugal distortion constants of ${\rm N}_2{\rm CO}$ are in comparison with experimental or theoretical data. The B3LYP results well reproduce the equilibrium geometries and spectroscopic constants. The anharmonic constants, vibration–rotation interaction constants, equilibrium sextic centrifugal distortion constants, Coriolis coupling constants, cubic and quartic force constants of ${\rm N}_2{\rm CO}$ are theoretically predicted. The results show that DFT methods can afford more reliable theoretical values than MP2 method.

A new potential energy surface (PES) of the $O_3$ system was reported, based on the PESs reported by Dawes et al. and Schinke et al. The PES of $O_3$ reported by Dawes et al. was fitted using least square method based upon accurate high level ab initio points, and has been applied to many dynamics calculations. However, it is computationally slow and need lots of time to obtain the energy points from the PES. At the same time, the threshold of the ab initio points is low as 2.6 eV, relative to the minimum of the PES, which limits its application. On the contrary, the PES reported by Schinke et al. numerically is fast and extends to high energy. In this work, we first calculated the energy points from these two PESs. Then we fitted these energy points using PIP-NN approach. In this way, a revised version of the PES of $O_3$ was constructed and we used it to perform quantum reactive scattering dynamics calculation.

We theoretically study the photofragmentation reaction of the hydrogen molecular ion $H^+_2$ by a single intense ultrashort laser pulse. Simulation results obtained from numerical solutions of time-dependent Schrödinger equations show that quantum interference patterns are constructed in the photofragment spectra and the induced angular distributions of photofragments are sensitive to the wavelength of the laser pulse. These phenomena are successfully explained by using the concept of the light-induced conical intersection.