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QUANTUM OPTIMAL CONTROL OF NUCLEAR MOTION AND PHOTODISSOCIATION USING GENETIC ALGORITHMAuthors: Sitansh Sharma,Harjinder Singh,Gabriel G Balint-Kurti Conference: Changing Paradigms of Theoretical and Computational Chemistry: From Atoms to Molecular Clusters Date: 2009-12-18 Report no: IIIT/TR/2009/190 AbstractConventionally optimal control theory [1, 2, 3] has been used in the theoretical design of laser pulses through the direct variation of the electric field of the laser pulse as a function of time. This often leads to designed laser pulses which contain a broad and seemingly arbitrary frequency structure that varies in time in a manner which may be difficult to realize experimentally. In contrast, in Genetic Algorithm (GA) approach, a few control parameters are used, which are actually available to the experimentalist. In this work, we investigate the possibility of using GA optimization methods in the theoretical design of laser pulses to bring about quantum state transitions in molecules. This allows us to select only a small limited number of parameters to vary and to choose these parameters so that they correspond to those available to the experimentalist. In this work, we apply our methods to the vibrational-rotational excitation of the HF molecule. We choose a small limited number of frequencies and vary only the associated electric field amplitudes and pulse envelopes. We show that laser pulses designed in this way can lead to very high transition probabilities. The mechanism of population transfer during the excitation process is investigated by projecting the laser driven nuclear wave function onto the eigenstates of the system. We have also investigated the possibility of photodissociation of HF molecule by climbing up the vibrational ladder using this genetic algorithm approach. Full paper: pdf Centre for Computational Natural Sciences and Bioinformatics |
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