New experimental techniques have enabled scientists to observe the

dynamics of atoms and molecules on their natural length (Angstrom) and

time (sub-femtosecond) scales. To simulate the quantum dynamics at the

nanoscale, we have developed a linear scaling, density functional theory

based atomistic computational approach that allows the study of the

behaviour of molecules, solids and nanostructures in time-dependent

external fields.   This real-space real-time density functional approach

couples the time-dependent Maxwell and Schroedinger equations, and

combined with the multidomain decomposition technique, enables the

simulation of realistic nanostructures containing thousands of atoms.

Examples will be presented for applications to study time-dependent

electron transport, laser induced field emission, radiation damage,

Coulomb explosion, laser surface interactions, attosecond imaging,

electron holography  and microscopy.