Globally accurate potential energy surface for PH₂⁺ (1¹ A′) by using the switching function formalism

Abstract

As an intermediate product of phosphorus compounds in astrophysical chemistry, ${\text{PH}}_2^{+}\left(1^1{\text{A}}^{\mathrm{\prime }}\right)$ has great significance in research on the ${\text{PH}}_{\text{n}}^{+}\left(\text{n}=0-4\right)$ systems. However, as a basis for studying its reaction mechanisms, ${\text{PH}}_2^{+}\left(1^1{\text{A}}^{\mathrm{\prime }}\right)$ lacks an accurate global potential energy surface (PES) and related dynamic reports. In this investigation, based on a multi-reference configuration interaction approach with Davidson correction, an accurate global many-body expansion PES for ${\text{PH}}_2^{+}$ in its ground state was reported by fitting extensive ab initio energies, as calculated with the correlation-consistent basis set aug-cc-pVQZ. Meanwhile, the switching function formalism was adopted to explain and distinguish the transformation between ${\text{P}}^{+}\left({}^1\text{D}\right)$ and ${\text{P}}^{+}\left({}^3\text{P}\right)$ in one-body energy terms, which ensured the correct dissociation channel in the reaction process of ${\text{P}}^{+}\left({}^1\text{D}\right)+{\text{H}}_2\left({\text{{X}}}^1{\mathrm{\Sigma }}_{\text{g}}^{+}\right)\to \text{P}{\text{H}}^{+}\left({\text{X}}^2\mathrm{\Pi }\right)+\text{H}\left({}^2\text{S}\right)$. The topographical characteristics of the title system PES were meticulously contrasted with those in other literature reports, which were consistent with previous experimental and theoretical values. Subsequently, the time-dependent wave packet approach was adopted to calculate the reaction probability and integral cross-section for the reaction ${\text{P}}^{+}\left({}^1\text{D}\right)+{\text{H}}_2\left({\text{{X}}}^1{\mathrm{\Sigma }}_{\text{g}}^{+}\right)\left(\text{v}=0,\text{j}=0\right)\to \text{P}{\text{H}}^{+}\left({\text{X}}^2\mathrm{\Pi }\right)+\text{H}\left({}^2\text{S}\right)$ to verify the accuracy of the new PES. This dynamics study may help to further explain the thermochemical reactions of phosphorus-containing molecules in interstellar media.

GRAPHICAL ABSTRACT

KEYWORDS:

• ${\text{PH}}_2^{+}\left(1^1{\text{A}}^{\mathrm{\prime }}\right)$
• ab initio
• potential energy surface
• switching function

Acknowledgments

This work was supported by the National Natural Science Foundation of China (grant number 11874241), the High-level Innovative Talents Program of Shenyang City (grant number RC180230), and the Shandong Province Higher Educational Science and Technology Program (Grant Nos. J15LJ03 and J17KA186).

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [grant number 11874241], the High-level Innovative Talents Program of Shenyang City [grant number RC180230], and the Shandong Province Higher Educational Science and Technology Program [grant numbers J15LJ03 and J17KA186].; Natural Science Foundation of Liaoning Province