Semiempirical quantum-chemical methods are well-established tools for computational studies of large molecules [1]. Methods with explicit orthogonalization corrections (OM1, OM2, OM3) offer better overall accuracy in standard statistical evaluations of ground-state properties as well as qualitative improvements in several areas [2]. OMx-based studies of electronically excited states employ a general implementation of the GUGACI approach in a semiempirical framework which provides analytic gradients and nonadiabatic couplings [3]. Comparisons with high-level ab initio benchmark data show that OMx-MRCI methods describe electronically excited states reasonably well [4]. They can thus be used in mixed quantum-classical dynamics [5] to investigate fast nonradiative relaxation processes after photoexcitation. Numerous such surface-hopping dynamics studies have been carried out at the OM2-MRCI level in recent years, which have addressed, for example, the complete photochemical cycle of a GFP chromophore with ultrafast excited-state proton transfer [6], the photodynamics of a prototypical Schiff base [7], and non-equilibrium H/D isotope effects for excited-state proton transfer in 7-(2-pyridyl)indole [8]. The lecture will address the theoretical background of surface-hopping dynamics and present selected OM2/MRCI applications.  [1]  W. Thiel, WIREs Comput. Mol. Sci. 2014, 4, 145-157. [2]  M. Korth, W. Thiel, J. Chem. Theory Comput. 2011, 7, 2929-2936. [3]  A. Koslowski, M. E. Beck, W. Thiel, J. Comput. Chem. 2003, 24, 714-726. [4]  M. R. Silva-Junior, W. Thiel, J. Chem. Theory Comput. 2010, 6, 1546-1564. [5]  E. Fabiano, T. W. Keal, W. Thiel, Chem. Phys. 2008, 349, 334-347. [6]  G. Cui, Z. Lan, W. Thiel, J. Am. Chem Soc. 2012, 134, 1662-1672.  [7]  L. Sp�rkel, G. Cui, W. Thiel, J. Phys. Chem. A 2013, 117, 4574-4583. [8]  L. Sp�rkel, G. Cui, A. Koslowski, W. Thiel, J. Phys. Chem. A 2014, 118, 152-157.

Surface hopping dynamics of excited-state proton transfer

248th National Meeting (2014)

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