where E max = E max,x î + E max,y ĵ + E max,z k is the amplitude vector and ω is the frequency of the oscillatory electric field. The molecular axes align best with the x-axis and the S 0 → S 1 transition possesses a large transition dipole moment along this axis; hence the field is chosen to be linearly polarized along the x-axis. The dipole moment matrices in the STO-3G basis, (µ x , µ y , µ z ) corresponding to the dipole moment operators (x, ŷ, ẑ), are obtained from the GAUSSIAN program. The timedependent dipole moment along each axis is given by: