Quantum diffusion wave-function approach to two-dimensional vibronic spectroscopy

We apply the quantum diffusion wavefunction approach to calculate vibronic two-dimensional ( 2D) spectra. As an example, we use a system consisting of two electronic states with harmonic oscillator potentials which are coupled to a bath and interact with three time-delayed laser pulses. The first-and second-order perturbative wave functions which enter into the expression for the third-order polarization are determined for a sufficient number of stochastic runs. The wave-packet approach, besides being an alternative technique to calculate the spectra, offers an intuitive insight into the dissipation dynamics and its relation to the 2D vibronic spectra. (C) 2014 AIP Publishing LLC.