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AMO Theoretical / Computational Physics |
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David R. Schultz Atomic Physics Group Leader Adjunct Professor Department
of Physics and Astronomy |
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Contact Information: David R.
Schultz Physics
Division Oak Ridge National Laboratory |
Collaborators Publications Short vita |
Research Interests
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For many decades,
theoretical study of the collision processes in plasmas and gases has relied
on increasingly sophisticated approximate solution of the time-dependent or
time-independent Schrödinger equation. Now, however, theoretical and
computational technique and computer facilities have advanced to the point
that direct, non-perturbative, lattice solution of quantum mechanical
collision problems in multiple dimensions is often feasible. This approach
avoids certain limitations and pathologies of conventional methods. The lattice approach for
solving the time-dependent Schrödinger equation addresses the goal of
understanding fundamental properties of atomic collision processes in naturally
occurring (e.g. atmospheric) and man-made (fusion energy, technical
processing) plasmas and gaseous environments. This work makes use of, and is,
in fact, enabled by, DOE high performance computing facilities at LBNL’s NERSC and the ORNL
CCS. It provides new insight into fundamental collisions systems and few-body
atomic problems as well as providing a vehicle for exploration of the
manipulation and control of atomic-scale systems (see Section 4.b). The
development and application to atomic collision problems of the lattice, time
dependent Schrödinger equation (LTDSE) approach has
been motivated in large part by the goal of avoiding a number of significant
approximations or pathologies of conventional approaches. It also stems from
the trend in atomic physics in which it has been possible to measure and
calculate certain quantities with great precision. For dynamic problems such as atomic
collisions or interactions of atoms with strong time-varying fields, even for
systems with only one or a few electrons, such a high precision description
of observables has not been achieved in calculations. The necessity to
describe the multielectron, multicenter
continuum, the need to represent processes driven through channels involving
states on more than one center, or involving the interaction among electrons,
are examples of inherent complexities that limit their accuracy. Therefore,
to treat photon-, electron- or ion-atom collisions, a wide range of
theoretical approaches have been devised which are applicable in various
regimes. An approach that can overcome many of the difficulties associated
with these methods is to solve the time-dependent Schrödinger equation as
directly as possible on a numerical lattice taking advantage of modern
techniques of computational science. Additional information can be found at Terascale Atomic Physics for Controlled Fusion |