Having a and b, the Fourier transform of µ λ (ω) can be constructed, and the result is that a shorter time sequence of input data is required to obtain a converged Fourier transform. In contrast to the Padé-accelerated transform technique that was introduced in Ref. 65, which introduces a representation based on occupiedvirtual function pairs ψ i (r, t) ψ a (r, t), the version that we have implemented transforms only the total dipole moment in Eqs. (10) and (11).