
AMO Theoretical / Computational Physics

Predrag S. Krstić

Senior Research Staff Member

AMO Theory

Physics Division

Oak Ridge National Laboratory

Adjunct Professor

Department of Physics and Astronomy

University of Tennessee

Contact Information:

Predrag S. Krstic

Physics Division

Oak Ridge National Laboratory
PO Box 2008, Bldg. 6010
Oak Ridge, TN 37831-6372
Tel. (865) 574-4701
Fax (865) 574-1118
krsticp@ornl.gov

Research Interests

Collaborators

Short vita

Selected Publications:

Collisions (atoms, molecules)

Plasma-Surface Interactions

Nano-Bio Physics

Laser-Atom Interactions

Patents

Invited Presentations and Contributions

Research Interests

My long-term interests and activities have been toward understanding of inelastic end elastic dynamics in nearly adiabatic heavy particle collisions, involving ions, atoms and molecules. To describe multitude of various processes, from electronic transitions, to ro-vibrationally resolved collisions, involving processes of charge transfer, excitation, ionization, dissociation and association, considered at the “same footing” whenever possible, a number of methods were developed or adopted, from fully quantum-mechanical to semiclassical and classical approaches. Choice of the collision constituents and the parameters has been often determined by the needs in modeling of the fusion edge and astrophysical plasmas. By the same token the cross sections have been calculated in the comprehensive form, with the controlled accuracy whenever possible, scanning wide ranges of collision energies and underlined processes, and disseminated through the CFADC web site.

My next current research interest is in the processes in plasma - material surface interactions, in the regime of interest for fusion plasmas as well as for the ORNL MIRF ion beam – surface experiments. Slow impacts of ions, atoms and molecules of hydrogen at carbons surfaces is very complex process, evolving through a collision cascade in the material, inducing various electronic processes, changing structure of the target material, and inducing various chemical reactions. Using modeling tools of classical molecular dynamics, and the best available hydrocarbon Born-Oppenheimer potentials, we study chemical sputtering, reflection, sticking, penetration, in function of surface structure, of a state of impact particle, of temperature and impact fluence in a 2D-periodic systems with a simulation cell of a few thousands of atoms, from amorphous structures to graphene.

My strong current interest is research of the mixed fusion materials, in particular Li-C-H-O+(W, Mo) systems. Besides developing new classical potentials, I am applying also quantum-mechanical tight-binding density functional theory methods. Essential for the validation of our results is collaboration with the experimental groups of Purdue University (J.P. Allain), PPPL (C. Skinner) and ORNL (F.W. Meyer).

Significant part of my research activities have been recently in the field of molecular and bio electronics. Nominally, this includes quantum mechanics of a large organo-metalic system, phenomenologically this is an electron scattering problem, where quasi-free Bloch electrons coming from the metallic leads and under influence of electric bias, through metal-molecule junction, scatter on the molecule, being transmitted with some probability to another lead. We have developed our own computational method for calculation of the electron transmission through a metal-organic system. Transmission through molecule certainly depends on its electronics structure, which is a motivating idea to study electron transport through the DNA nucleotides and seek a possibility of sequencing of a DNA by measurement of conductance of its bases. Monomer and polymer self-assembly at a metals substrate is one of a strongly highlighted advantages of molecular electronics. We study such formations by developing interacting potentials and relevant forces through computational chemistry energy calculations of adequate metal-organic clusters. Essential for these developments has been collaboration with the ORNL Center for Nanophase Material Sciences, in particular with Xiaoguang Zhang.

My strong current interest is application of both continuum (COMSOL) and classical molecular dynamics methods to study micro-nano fluid dynamics through carbon nanotubes and aqueous Paul nanotrap, in order to develop the methods for DNA control and localization in the physical methods of the DNA sequencing. Electrophoretic, dielectrophoretic, electroosmotic, and diffusion fluxes are essential carriers of the translocation of the DNA segments through the devices. This research is also enriched by the quantum approach to the energetics and charging of the CNT as well as molecular DNA readers. Collaborations with the experimental groups of Arizona State University (Stuart Lindsay) and Yale University (Mark Reed) are essential for both inspiration and validation of our theoretical research in this field.

Multiphoton processes, mainly in nonperturbative strong filed regime, and mainly multiphoton ionization, were my first interest in theoretical atomic physics from late seventies of the last century. Motion of a bound or a free electron in the ultrastrong laser field is relativistic, which has for a consequence an effective change of the electron rest mass (nonrelativistically seen as a ponderomotive potential) as well as strong beyond-dipole effects. Particularly exciting in ionization in the limit of strong laser stabilization of atoms against ionization in the limit of strong laser fields.

My strong current research interest is to fully understand a role of electron-electron correlations in a few-electron systems interacting with photons. This underlines a development of a computationally highly intensive tools for numerical solution of the multielectron Schrodinger equation in dynamical regime, including methods of computational chemistry, various time-propagation and variable-step space discretization schemes, and quantum-classical molecular dynamics. Essential for this research has been collaboration with Robert Harrison of ORNL and his computational-chemistry group.