Matlab code for computation of transitions through avoided crossings using superadiabatic representations.
See e.g. Wave packet dynamics in the optimal superadiabatic approximation
V. Betz, B. D. Goddard, and U. Manthe
The Journal of Chemical Physics 144, 224109 (2016) doi: 10.1063/1.4953577
Open access: http://www.research.ed.ac.uk/portal/files/25669999/NaI_trans_JCP.pdf
We explain the concept of superadiabatic representations and show how in the context of electronically non-adiabatic transitions they lead to an explicit formula that can be used to predict transitions at avoided crossings. Based on this formula, we present a simple method for computing wave packet dynamics across avoided crossings. Only knowledge of the adiabatic potential energy surfaces near the avoided crossing is required for the computation. In particular, this means that no diabatization procedure is necessary, the adiabatic electronic energies can be computed on the fly, and they only need to be computed to higher accuracy when an avoided crossing is detected. We test the quality of our method on the paradigmatic example of photo-dissociation of NaI, finding very good agreement with results of exact wave packet calculations.
Research data associated with this code can also be found on DataShare - http://datashare.is.ed.ac.uk/handle/10283/2646
Goddard, Benjamin. (2017). Wave packet dynamics in the optimal superadiabatic approximation - Matlab code, [software]. http://dx.doi.org/10.7488/ds/1989.