We introduce a first-principles molecular dynamics method based on the discretized path integral representation of quantum particles. Fermi statistics is automatically generated by an effective exchange potential. This path-integral molecular dynamics method is able to simulate exchange in electron plasmas at the border of the degenerate regime with a satisfactory level of accuracy. [S0031-9007(98)07262-7]
The path-integral molecular-dynamics method is employed to study the effect of temperature on a simple metal ͑potassium͒ model system. The simple metal undergoes a phase transformation upon heating. Calculated dynamic properties indicate that the atomic motion changes from a vibrational to a diffusive character identifying the transformation as melting. Calculated structural properties further confirm the transformation. Ionic vibrations in the crystal state and the loss of long-range order during melting modify the electronic structure and in particular localize the electrons inside and at the border of the ion core.
The usefulness of the restricted path integral molecular dynamics method for the study of strongly correlated electrons is demonstrated by studying the formation of bound electronic states in a half-filled expanded three-dimensional hydrogenoid body-centred cubic lattice at finite temperature. Starting from a metallic state with one-component plasma character, we find that bound electrons form upon expansion of the lattice. The bound electrons are spatially localized with their centre for the motion of gyration located at ionic positions. The number of bound electrons increases monotonically with decreasing density.
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