Infrared absorbing electron in ice-Ih is trapped by a water vacancy

Ionization of polar liquids and glasses often yields metastable electron centers collectively known as weakly bound (wb) electrons that absorb to the red of the ground state of the solvated/trapped electron. Formation of these species is thought to be the initial stage of electron localization in such media. Although these commonly occurring species have distinctive absorption spectra, no insight into their structure currently exists. In this Letter, we address the structure of the wb electron in low-temperature ice-Ih theoretically, using a combination of mixed quantum-classical (MQC) floating set of Gaussian orbitals (FSGO) - Metropolis Monte Carlo (MC) method and embedded cluster density functional theory (DFT) post treatment. The comparison with the observed properties of the wb electron in ice suggests that this species is an s-like wavefunction filling a water vacancy.