Theoretical study of photoisomerisation processes involving a conical intersection

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The aim of the project is to study photoisomerisation processes which involve conical intersections. For this several problems have to be solved.(i) As one is dealing with comparatively large molecules (9 to 30 degrees of freedom, say) it is appropriate to use a model Hamiltonian. A well known example of such an approach is the vibronic coupling Hamiltonian [1]. However, this model is applicable for small amplitude motion only, whereas isomerisation involves large amplitude motion of at least a few coordinates. Hence it is our aim to develop a model Hamiltonian in curvilinear coordinates which is more general and more suitable for our purposes.(ii) The derivation of the kinetic energy operator in curvilinear coordinates is a cumbersome and difficult task. This task shall be automatised. The ultimate solution would be a program which writes a so called operator file for the MCTDH program.(iii) The MCTDH program has to be further developed such that it can parse and process the automatically generated operator file. Furthermore, as comparatively large molecules are to be investigated, one needs to improve the performance of MCTDH on these large systems.(iv) The application calculations simulating the photo-induced isomerisation processes have to be performed using the Heidelberg MCTDH package.