Theoretical study of resonance formation in microhydrated molecules. I. Pyridine-(H 2 O) n , n = 1,2,3,5.

We present R-matrix calculations for electron scattering from microhydrated pyridine. We studied the pyridine-H2 O cluster at static-exchange (SE), SE + polarization, and close-coupling levels, and pyridine-(H2 O)n n = 2, 3, and 5 at SE level only in order to investigate the effect of hydrogen bonding on the resonances of pyridine. We analyse the results in terms of direct and indirect effects. We observe that the total (direct plus indirect) effect of microhydration leads to the stabilization of all resonances studied, both shape and core-excited. The size of the shift is different for different resonances and seems to be linked to the dipole moment of the cluster.