Ab Initio Vibrational Spectroscopy of Water and Aqueous Solutions in a Wide Pressure–Temperature Range

Vibrational spectroscopy is commonly applied for investigating the chemical and physical properties of water and aqueous solutions. Ab initio spectroscopy methods are used to analyze experimental spectra, offering valuable insights into structural and dynamic properties. In cases where experimental data is limited or contentious for aqueous systems subjected to high pressure–temperature conditions or extreme spatial confinement, ab initio methods can provide guidance for experiments. Recent progress in algorithms and computational power has driven substantial development in ab initio spectroscopy. In this review, we summarize first principles methods for calculating dipole moments and electronic polarizabilities, as well as demonstrate the use of time correlation functions for calculating infrared (IR) and Raman spectra. Additionally, we summarize recent advances in machine learning methods developed to expedite spectrum calculations and discuss the existing challenges that require further advancements in the field.