STSM by Cristina Sanz-Sanz, Department of Physical Chemistry, Universidad Autónoma de Madrid with Graham Worth, School of Chemistry, University of Birmingham
On September 23rd, 2013 (10 days)
From SPAIN to UNITED KINGDOM
Fitting of field dependent potential energy curves, spin-orbit and elements of the dipole moment matrix of the first 36 states of IBr
The control of the photodissociation of IBr through a curve crossing was studied in the group of Prof. Stolow using the dynamic Stark effect. Until now, theoretical simulations have used a reduced model including just 3 electronic states. However, the system consists on 36 electronic states dissociating to the ground states of atoms. We have computed and fitted the 36 potential energy curves, spin-orbit and elements of the dipole matrix for several electric field strengths and orientations. Those curves will be used in the dynamical calculations to reproduce the experiment.
The electronic structure calculation programs do not maintain the phase of the wavefunction and it translates into jumps in the spin-orbit and transition dipole moment curves. In order to use these curves in dynamical calculation programs the curves have to be fitted. Because of the sudden changes in the curves normal fitting methods do not work. We have used an optimization method to smooth out the spin-orbit and transition dipoles.
During the STSM visit we finished with the fittings of the potential energy curves, spin-orbit couplings and the elements of the dipole moment matrix for several electric field strengths and orientations. The dynamical calculations will be done using MCTDH package and we created the input files and fittings required for the wavepacket calculations. A test calculation was done for a free field example using the 36 spin-orbit states. In addition, we wrote the outline of the first publication of a series of works that will include the global fittings of potential energy curves, spin-orbit couplins and dipole moment matrix.