Most materials, when heated to temperatures exceeding a few thoudand
Kelvin, become fluid metals composed of ions and degenerate electrons. We have been conducting fundamental
researches on the properties of "warm dense matter" located between
low-temperature solids and hot ionzized gases.
When an expanding liquid metal enters the gas phase through the supercritical
state, electrons are eventually localized at each atomic site, exhibiting
a metal-nonmetal transition. By combining quantum-chemical analysis of clusters [1] and statistical theory of liquids, we have succesfully reproduced the gas-liquid coexistence
curve and critical point of mercury from first principles [2] (see the
figure below). Cluster-variation method has been employed to calculate
the critical point of fluid alkali metals [3].
Quantum dynamics of electrons in fluid metals is also a subject of great
significance in relation to x-ray scattering experiments. Emergence of
inhomogeneous density distributions [4] in expanded fluid metals can influence
Compton scattering profiles [5].
Fig. 1: Gas-liquid coexistence curve of mercury on the mass density-temperature plane.