  The interaction of laser fields with solid-state systems can be modeled
efficiently within the velocity-gauge formalism of real-time time dependent
density functional theory (RT-TDDFT). In this article, we discuss the
implementation of the velocity-gauge RT-TDDFT equations for electron dynamics
within a linear combination of atomic orbitals (LCAO) basis set framework.
Numerical results obtained from our LCAO implementation, for the electronic
response of periodic systems to both weak and intense laser fields, are
compared to those obtained from established real-space grid and Full-Potential
Linearized Augumented Planewave approaches. Potential applications of the LCAO
based scheme in the context of extreme ultra-violet and soft X-ray
spectroscopies involving core-electronic excitations are discussed.

Materials Science