# Physics Division

## Physics Division Seminars

Physics Division Seminars bring us speakers on a variety of physics
related subjects. Usually these are held in the Building 6008
large Conference Room, at 3:00 pm on the chosen day, but times
and locations may vary. For more information, contact our seminar
chairman,

Alfredo Galindo-Uribarri

Tel (Office): (865) 574-6124 (FAX): (865) 574-1268

#### Thu., May 24, 2007, at 3:00 p.m. (refreshments at 2:40 p.m.)

### Complex Absorbing Potentials in Multichannel Scattering and Photofragmentation Dynamics of Atomic and Molecular Systems

*Ronald McCarroll, Université Pierre et Marie Curie, Paris, France*

Building 6008 Conference Room

The first applications of complex absorbing potentials (CAPs) were related to the treatment of the positions and widths of scattering resonances. Being non-zero only in the asymptotic region, their role is to convert outgoing waves into exponentially decaying functions, thereby allowing for the use of L2 (basis expansion) methods. In time-dependent (or wave packet propagation) methods, CAPs are introduced to absorb spurious reflections at the boundaries of finite grids In both time dependent and time independent descriptions of scattering processes, the introductions of CAPs converts outgoing into absorbing boundary conditions (ABC) which led to applications in the description of reactive scattering and photofragmentation processes.

In the seminar, some recent applications of CAPs to a variety of dynamical processes in atomic and molecular systems will be presented. Most of these require descriptions which involve non-adiabatic, relativistic and isotopic effects in multichannel scattering processes. By enabling the use of an L2 basis, such as a discrete variable representation (DVR), the introduction of CAPs makes it possible to treat bound and continuum states on the same footing. The relation of CAPs with complex scaling techniques will also be discussed.