Molecular dynamics multiple states electronic structure

Recently, there has been much interest in the development and application of multidimensional coherent nonlinear femtosecond techniques for the study of electronic and vibrational dynamics of molecules [1], In such experiments more than two laser pulses have been used [2-4] and the combination of laser pulses in the sample creates a nonlinear polarization, which in turn radiates an electric field. The multiple laser pulses create wave packets of molecular states and establish a definite phase relationship (or coherence) between the different states. The laser pulses can create, manipulate and probe this coherence, which is strongly dependent on the molecular structure, coupling mechanisms and the molecular environment, making the technique a potentially powerful method for studies of large molecules. 

Changes in the electronic and molecular structures of a molecule A due to a transition from its ground to an excited state can result in creation of conditions for chemical bonding between the excited molecule A (in the whole review the symbol A will denote an excited particle A in general the number X in the symbol XA denotes the multiplicity of the excited particle A), and another molecule Q of the system, giving rise to an excited adduct (A — Q) [1], Such an adduct formed in a bimolecular dynamic adiabatic process... 

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