Application of the wave packet molecular dynamics to simulation of nonideal plasmas at moderate temperatures

Complete text of publication follows. Atomistic simulation of matter at extreme conditions allows one to study equilibrium systems and relaxation processes at the microscopic level. The method of classical molecular dynamics is successfully applied to study nonideal (strongly coupled) plasmas at moderate densities (about 1021cm-3 for H plasma) and relatively high temperatures (over 104K). At lower temperatures and/or higher densities the use of the electron-ion and electron-electron pseudopotentials introduces considerable ambiguity in the plasma thermodynamics and relaxation rates. Quantum methods such as DFT, applied to plasma simulations, are much more computationally demanding than the classical MD. Moreover, these methods are mostly not capable to handle the dynamics of electrons. Wave packet molecular dynamics method (WPMD) is the approach introducing quantum features in the classical electron dynamics. The electron-ion interaction model resulting from WPMD may be regarded as a kind of ab-initio pseudopotential, free from empirical parameters. The area of very high plasma densities (about 1023cm-3 for H plasma) and low temperatures (less than 104K) is well described by the WPMD methods including the version with fully antisymmetrized wave functions for electrons with the same spin. These methods, however, are not directly applicable to higher temperatures due to the model breakdown caused by spreading of the wave packets for weakly bound electrons. In this report we introduce an approach to simultaneous description of non-localized and bound electrons within the WPMD method. This approach is based on the numerical separation of the elastically and non-elastically colliding particles in course of the simulation. The elastic collisions are treated by the classical Coulomb model, whereas for non-elastic processes a version of the WPMD algorithm is applied. Application of the model to the case of hydrogen plasma is considered. Our approach allows one to consistently describe various bound states (at the accuracy level of a single Gaussian per electron) and the ionization balance within the plasma. A comparison of the results to other theoretical and experimental data is discussed.