An ab initio treatment of liquid oxygen: investigating density functional impact

Liquid oxygen at high pressures is of interest due to the presence of oxygen-rich compounds in astrophysical processes and detonation products. As such, an accurate description of the equation of state and electronic properties is essential to capture the correct behavior in models utilizing this information. A theoretical treatment can be challenging due to the need to accurately capture Van der Waals interactions and accurately describe molecular dissociation, ionization, and excited states. Ab initio Molecular Dynamics (AIMD) utilizing Density Functional Theory (DFT) is a common method of choice that has qualitatively reproduced features of the Hugoniot. Previous theoretical works have demonstrated that the choice of functional can impact the calculated Hugoniot and related values. In this work, we explore Liquid oxygen with AIMD with an interest in investigating how the choice of functionals can impact the properties of interest. To address the variation caused by the density functional, a quantum Monte Carlo analysis is done. SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525.