The method of ab initio molecular dynamics, based on finite-temperature density-functional theory, is used to simulate laser heating of crystalline silicon. We found that a high concentration of excited electrons dramatically weakens the covalent bonding. As a result the system undergoes a melting transition to a metallic state. We studied several structural, dynamical, electronic, and bonding properties of this phase of silicon. In contrast to ordinary liquid silicon, this liquid is characterized by a high coordination number and a strong reduction of covalent-bonding effects. However this phase is transient. In fact, by strongly reducing the level of electronic excitation, liquid silicon reverts very rapidly to its usual properties.

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Journal Phys. Rev. B
Silvestrelli, P. L, Alavi, A, Parrinello, M, & Frenkel, D. (1997). Structural, dynamical, electronic, and bonding properties of laser-heated silicon: An ab initio molecular-dynamics study. Phys. Rev. B, 56, 3806–3812.