High-Accuracy ab Initio Rotation-Vibration Transitions for Water

TLDR

The water vapor spectrum is crucial for atmospheric processes, creating an urgent need for a robust, accurate predictive model. The study reports first‑principles calculations of the high‑resolution water spectrum that approach experimental accuracy. The authors performed exceptionally large electronic structure calculations and incorporated effects such as quantum electrodynamics, often neglected in small many‑electron molecules. The ab initio procedure achieves high accuracy for the main isotopomers of water.

Abstract

The spectrum of water vapor is of fundamental importance for a variety of processes, including the absorption and retention of sunlight in Earth's atmosphere. Therefore, there has long been an urgent need for a robust and accurate predictive model for this spectrum. In our work on the high-resolution spectrum of water, we report first-principles calculations that approach experimental accuracy. To achieve this, we performed exceptionally large electronic structure calculations and considered a variety of effects, including quantum electrodynamics, which have routinely been neglected in studies of small many-electron molecules. The high accuracy of the resulting ab initio procedure is demonstrated for the main isotopomers of water.