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Andreas D. Koutselos Professor Chemistry Phone: 30 210 7274 536
Research
Interests The dynamic and kinetic phenomena of
systems out of equilibrium have entered a new phase due to advances in
selective monitor experimental techniques.
Systems that interest us involve chemical solutions constrained away
from equilibrium and ions moving in fluids under the action of external
fields. Such systems undergo
rotational, vibrational and electronic excitation
and relaxation, as well as, chemical transformations that vary from those
that appear close to equilibrium. The
new experimental observations require the development of theoretical tools
that treat few-body interactions sampled with statistics of microscopic
properties that emerge far from equilibrium.
Especially, the excitation of internal molecular degrees requires the
use of quantum methods for their description, though at low temperatures even
the translational motion requires a similar treatment. In addition, the statistical distribution
of microscopic properties has to be calculated accurately depending on
microscopic interactions and macroscopic constraints. We use stochastic theory for the
description of dense reactive systems [1] and kinetic theory calculations for the
transport of ions in low density fluids [2].
Complex molecular systems, such as many atom complexes, nanoparticles and oligopeptides,
are more easily amenable to study through molecular dynamic (MD)
simulation. In this case we have
developed MD methods that efficiently reproduce the experimental transport
and relaxation data of the ions in fluids, from low to intermediate density,
and for the whole experimental electric field range [3]. [1] "Steady State Thermodynamics for
Homogeneous Chemical Systems" A. D. Koutselos, J. Chem. Phys. 101, 10866, (1994). [2] a) "Third Order
Transport Properties of Ions in
Electrostatic Fields", A. D. Koutselos, J. Chem. Phys. 110, 3256, (1999). [3] a) "Transport and
dynamic properties of O2+ (X2Ðg) in Kr under the action of an electrostatic
field: Single or multiple
potential energy surface treatment",
A. D. Koutselos, J. Chem. Phys. 134, 194301 (2011). b) "Mixed quantum-classical
molecular dynamics simulation of
vibrational relaxation of ions in an
electrostatic field", A. D.
Koutselos, J. Chem. Phys. 125,
244304 (2006). c) "Molecular dynamics simulation of ion transport
in moderately dense gases in an electrostatic field", G. Balla and A. D.
Koutselos, J. Chem. Phys. 119,
11374 (2003). d) "Transport properties of diatomic ions in
moderately dense gases in an electrostatic field", A. D. Koutselos and
J. Samios, Pure Appl. Chem. 76,
223 (2004). |
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Research Work of
Graduate Students: Maria Anagnostopoulou
The experimental measurements of
the mobility of ions at very low temperature noble gases have shown an
unexpected deep that has not been explained fully so far. We study this system through a nonequilibrium molecular dynamics method with the use of
an effective cooling technique. This
system requires a quantum treatment for the translational motion, which is
implemented here through a semi-classical variational solution of the
Schrödinger equation based on a trial bosonic
wave function that is constructed from single particle wave packets. Iraklis Litinas
The motion of peptide ions (Ac-A14KG3A14K+2H+ in a noble gas) in drift tube measurements presents an abrupt change at high temperature that is speculated to be due to the variation of the ion-neutral collision cross section. If such a change is due to a temporary unfolding of the oligopeptide at high temperature then it should show up in the accumulation of energy of the bending mode involved in the peptide transformation. This system is a prototype for the study of peptide transformations in ion mobility spectrometry and its transport properties are reproduced here through an MD simulation method that treats molecular translation, rotation and bending motion explicitly through a model interaction potential. |
