Very-high-temperature molecular dynamics

It is shown that a modified scheme of density functional theory, using the Thomas-Fermi kinetic energy functional for the electrons, is well suited to perform very-high-temperature molecular dynamics simulations on high-$Z$ elements. As an example, iron on the principal Hugoniot is simulated up to $5\mathrm{keV}$ and 5 times the normal density, giving an equation of state in agreement with current models. Ionic structure is obtained and is given to an excellent level of precision by the structure of the one-component plasma computed for a coupling parameter corresponding to Thomas-Fermi ionization.

Figure 1

Bare Coulomb potential compared with the SI potential given by Eq. (5) and with the NC potential given by Eq. (11) with the same cutoff $r_c=1.33$ atomic units for $Z=1$.

Figure 2

Principal Hugoniot of iron. Line is SESAME EOS, circles are TFMD results, and squares come from QMD.

Figure 3

Ion-ion pair distribution functions. Circles represent our results, and the line is the OCP one computed with the effective ${\Gamma }^{*}$.