Equilibrium fractionation of H and O isotopes in water from path integral molecular dynamics

摘要: The equilibrium fractionation factor between two phases is of importance for the understanding many planetary and environmental processes. Although thermodynamic can be achieved minerals at high temperature, natural processes involve reactions liquids or aqueous solutions solids. For crystals, a theoretically determined using statistical approach based on vibrational properties phases. These calculations are mostly performed in harmonic approximation, empirical ab-initio force fields. In case aperiodic dynamic systems such as solutions, similar done finite-size molecular clusters snapshots obtained from dynamics (MD) runs. It however difficult to assess effect these approximate models isotopic properties. this work we present systematic study calculation D/H 18 O/ 16 O factors water liquid/vapour ice/vapour several levels theory within simulations. Namely, use integration Path Integral MD (PIMD) an potential model water. Compared with standard MD, PIMD takes into account quantum effects modeling exact given obtained. We compare results those strategies usually used, which mapping system its counterpart. show including configurational disorder estimation isotope liquid addition, convergence function parameters size simulated multiple substitution analyzed, showing that essentially local investigated system. 2014 Elsevier Ltd. All rights reserved.