STRUCTURAL, DYNAMICAL, ELECTRONIC, AND BONDING PROPERTIES OF LASER-HEATED SILICON - AN AB-INITIO MOLECULAR-DYNAMICS STUDY

The method of ab initio molecular dynamics, based on finite-temperatur e density-functional theory, is used to simulate laser heating of crys talline silicon. We found that a high concentration of excited electro ns dramatically weakens the covalent bonding. As a result the system u ndergoes a melting transition to a metallic state. We studied several structural, dynamical, electronic, and bonding properties of this phas e of silicon. In contrast to ordinary liquid silicon, this liquid is c haracterized by a high coordination number and a strong reduction of c ovalent-bonding effects. However this phase is transient. In fact, by strongly reducing the level of electronic excitation, liquid silicon r everts very rapidly to its usual properties.