Rovibronic spectroscopy of PN from first principles

TL;DR

This paper presents a comprehensive ab initio study of the rovibronic spectra of phosphorous mononitride (PN), including potential energy surfaces, coupling curves, and simulated spectra, validated against experimental data.

Contribution

It provides the first detailed ab initio calculations of multiple electronic states and their rovibronic spectra of PN, including transition properties and lifetimes, using high-level electronic structure and nuclear motion methods.

Findings

Good agreement of calculated A¹Π state lifetime with experimental data.

Accurate simulation of rovibronic spectra at different temperatures.

Complete set of potential and coupling curves for nine electronic states.

Abstract

We report an ab initio study on the rovibronic spectroscopy of the closed-shell diatomic molecule phosphorous mononitride, PN. The study considers the nine lowest electronic states, $X\,{}^{1}\Sigma^{+}$, $A\,{}^{1}\Pi$, $C\,{}^{1}\Sigma^{-}$, $D\,{}^{1}\Delta$, $E\,{}^{1}\Sigma^{-}$, $a\,{}^{3}\Sigma^{+}$, $b\,{}^{3}\Pi$, $d\,{}^{3}\Delta$ and $e\,{}^{3}\Sigma^{-}$ using high level electronic structure theory and accurate nuclear motion calculations. The ab initio data cover 9 potential energy, 14 spin-orbit coupling, 7 electronic angular momentum coupling, 9 electric dipole moment and 8 transition dipole moment curves. The Duo nuclear motion program is used to solve the coupled nuclear motion Schr\"{o}dinger equations for these nine electronic states and to simulate rovibronic absorption spectra of $^{31}$P$^{14}$N for different temperatures, which are compared to available spectroscopic studies. Lifetimes for all states are calculated and compared to previous results from the literature. The calculated lifetime of the $A\,{}^{1}\Pi$ state shows good agreement with an experimental value from the literature, which is an important quality indicator for the ab initio $A$-$X$ transition dipole moment.