W4 thermochemistry of P_2 and P_4. Is the CODATA heat of formation of phosphorus atom correct?

TL;DR

This study uses high-accuracy computational methods to reassess the thermochemistry of phosphorus molecules, confirming the experimental data's validity and providing refined heats of formation that challenge previous CODATA values.

Contribution

The paper applies advanced W4 and post-W4 computational methods to accurately determine phosphorus thermochemistry, offering a revised heat of formation for atomic phosphorus.

Findings

Experimental thermochemistry is validated.

Significant post-CCSD(T) correlation effects identified.

Revised heat of formation for phosphorus atom provided.

Abstract

The high-accuracy W4 computational thermochemistry protocol, and several post-W4 methods, have been applied to the P$_2$ and P$_4$ molecules. Contrary to previous studies, we find the experimental thermochemistry to be fundamentally sound. The reaction enthalpy for P$_4\to 2$P$_2$ has a very significant contribution from post-CCSD(T) correlation effects. We derive a gas-phase heat of formation for the phosphorus atom of $\Delta H^\circ_{f,0}$[P(g)]=75.54$\pm$0.1 kcal/mol and $\Delta H^\circ_{f,298}$[P(g)]=75.74$\pm$0.1 kcal/mol, in the upper half of the CODATA uncertainty interval.