Unraveling correlation effects in water from microscopic response functions*

Electronic correlation effects play a crucial role in determining the structural and chemical properties of water. Over past decades, first-principles theory has been widely used to obtain physical insights of water and interpret experimental results. However, direct analysis of the electronic correlation in water from first principle is non-trivial, which motivates the development of new descriptors based on the microscopic response functions and formal methodologies to efficiently evaluate them. Recently, we have developed an ab initio local dielectric response theory [Phys. Rev. B 92, 241107, 2015] that partitions the microscopic electric susceptibility in real space based on the Wannier representation. Several applications of the local dielectric response theory are discussed. We demonstrate how to compute the molecular polarizability of water in the condensed phase and analyze the effects of the hydrogen-bonded network resulting from the crystal field and charge transfer. In another example, we studied the non-local correlation behaviors between water and solvated ions, and identified different screening characteristics of longitudinal and transverse modes.