IIIT Hyderabad Publications |
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Application of Optimal Control Theory to Control Nuclear Motion in MoleculesAuthors: Harjinder Singh Conference: Invited Talk: Discussion Meeting on Theoretical Chemistry, SSCU, IISc Centenary Conference Bangalore, January 18-22, 2009. Date: 2009-09-01 Report no: IIIT/TR/2009/124 AbstractOptimal control theory (OCT) has emerged as one comprehensive means of designing laser pulses for achieving prescribed dynamical goals. A detailed analysis of the optimal pulse reveals complex pathways to arrive at seemingly simple goals. We have used OCT to obtain infrared laser pulses for the selective vibrational excitation of several different systems, from simple diatomic to triatomic systems located in complex molecular environments. We will present our results obtained for the diatomic system HF applying OCT using different algorithmic methods, namely an iterative method, conjugate gradient method and genetic algorithms. We look at the validity and relevance of the pulse area theorem in this context. The results of a new dynamic method for applying the penalty term needed to keep the power in the electric field of the laser within reasonable bounds will be discussed. For the triatomic FeCO and the hydrogen bonds NHO/NHN in a A-T base pair, we use two mathematical dimensional models. Density functional theory is used to obtain the potential energy and dipole moment surfaces of the active site model. The Conjugate gradient method is employed to optimize the cost functional and to obtain the optimized laser pulses. Optimized laser fields are found which give virtually 100% excitation probability to preselected vibrational levels. We will discuss our ongoing work on formulating the problem of photodissociation of the FeCO entity in carboxymyoglobin using OCT. Centre for Computational Natural Sciences and Bioinformatics |
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