Formation of phosphorus monoxide through the reaction

Area of Science:

• Astrochemistry
• Theoretical Chemistry
• Chemical Kinetics

Background:

• Phosphorus is essential for life, and its interstellar availability is key to understanding life's origins.
• The phosphorus oxide (PO) molecule is a significant reservoir of phosphorus in the interstellar medium (ISM).
• Accurate modeling of PO abundances requires understanding its formation mechanisms and rate coefficients in the ISM.

Purpose of the Study:

• To investigate the formation of the PO molecule via the O + P reaction.
• To analyze the potential energy surface and calculate rate coefficients for PO formation on both doublet and quartet states.
• To compare theoretical calculation results with experimental data.

Main Methods:

• Multireference configuration interaction (MRCI) calculations were employed to study the potential energy surface of the OPO system.
• Density Functional Theory (DFT) and Coupled Cluster (CCSD(T)) calculations were performed for comparison.
• The master equation system solver (MESS) package was used to compute rate coefficients.
• Calculated rate coefficients were compared with recent experimental data.

Main Results:

• The OPO system exhibits significant multiconfigurational character, indicating that DFT and CCSD methodologies are unsuitable for its potential energy landscape.
• The calculated rate coefficients were accurately described by a modified Arrhenius equation.
• The quartet state significantly contributes to PO formation at temperatures above 700K.

Conclusions:

• The study provides crucial insights into the formation pathways and kinetics of the PO molecule in the interstellar medium.
• Accurate theoretical methods are essential for studying systems with high multiconfigurational character.
• The findings contribute to a better understanding of phosphorus chemistry in space and its implications for astrobiology.