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Mark Thachuk


Research and Teaching Interests

My research interests involve the study of the dynamics of chemical reactions/processes using mathematical and computational techniques. Currently, there are two main themes in my research group: studying collision-induced alignment of gas-phase ions, and examining the dissociation mechanism for gas-phase protein complexes

Collision-Induced Alignment

When ions or molecules move through a gas preferentially in one direction, they develop a preferred alignment. This motion can be induced by putting a charged ion in a bath gas with an external electric field, or by expanding a seed molecule in a molecular beam expansion, or even by injecting gas phase ions with high velocities directly into a bath gas. My group uses molecular dynamics simulations to model these kinds of experiments, with the goal of understanding the underlying mechanism for collision-induced alignment, and its dependence upon molecular parameters, such as charge and mass distribution.

Current projects include studying collision-induced alignment in non-linear ions, and determining whether this mechanism can be used to produce experimentally-tuned and isolated aligned molecules in the gas phase. In a similar vein, we are also examining the transition in the description of diffusion and mobility on moving from a Boltzmann regime (in which only uncorrelated binary collisions are important) to a hydrodynamic regime.

Dissocation of Gas-Phase Protein Complexes

Recent experiments examining the dissocation of non-covalent, gas-phase protein complex ions have discovered that under certain conditions, charge asymmetry can occur in the fragment ions. For example, a dimer of cytochrome c with a charge of 11+ yields predominantly on dissociation monomers with charges of 8+ and 3+ rather than the more symmetric 6+ and 5+ combination. It has been proposed that in the dissociation mechanism, one of the monomers in the complex unfolds, and this leads to the charge asymmetry. One active project involves using molecular dynamics simulations to examine this dissociation mechanism.

Beyond this though, we would like to develop simple models to treat this phenomenon, including extending reaction path models, and/or coarse-graining techniques to treat complex systems. One would like to capture the essential physics of this process without resorting to atomistic level simulations.



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D 328
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Curriculum Vitae

B. Sc., Western Ontario (1986); Ph.D., Waterloo (F.R.W. McCourt, 1991); Postdoctoral, Northwestern (G.C. Schatz, 1991-1993) and Queen's, Kingston (D.M. Wardlaw, 1993-1996).



Wanasundara, S. N. ; Thachuk, M. Toward An Improved Understanding Of The Dissociation Mechanism Of Gas Phase Protein Complexes. Journal of Physical Chemistry B 2010, 114, 11646 - 11653.


Wanasundara, S. N. ; Thachuk, M. Free Energy Barrier Estimation For The Dissociation Of Charged Protein Complexes In The Gas Phase. Journal of Physical Chemistry A 2009, 113, 3814-3821.


MacDonald, B. I. ; Thachuk, M. Gas-Phase Proton-Transfer Pathways In Protonated Histidylglycine. Rapid Communications in Mass Spectrometry 2008, 22, 2946-2954.


Wanasundara, S. N. ; Thachuk, M. Theoretical Investigations Of The Dissociation Of Charged Protein Complexes In The Gas Phase. Journal of the American Society for Mass Spectrometry 2007, 18, 2242-2253.


Chen, X. ; Thachuk, M. Collision-Induced Alignment Of H2O+ Drifting In Helium. Journal of Chemical Physics 2006, 124, 8.


Chen, X. ; Thachuk, M. Ground And First-Excited Global Potential Energy Surfaces Of The H2O+-He Complex: Predictions Of Ion Mobilities. International Journal of Quantum Chemistry 2005, 101, 1-7.
McCourt, F. R. W. ; Weir, D. ; Clark, G. B. ; Thachuk, M. Transport And Relaxation Properties Of Isotopomeric Hydrogen-Helium Binary Mixtures. I. H-2-He Mixtures. Molecular Physics 2005, 103, 17-36.
McCourt, F. R. W. ; Weir, D. ; Thachuk, M. ; Clark, G. B. Transport And Relaxation Properties Of Isotopomeric Hydrogen-Helium Binary Mixtures. Ii. Hd, D-2, T-2-He Mixtures. Molecular Physics 2005, 103, 45-58.


Csiszar, S. ; Thachuk, M. Using Ellipsoids To Model Charge Distributions In Gas Phase Protein Complex Ion Dissociation. Canadian Journal of Chemistry-Revue Canadienne De Chimie 2004, 82, 1736-1744.


Chen, X. ; Araghi, R. ; Baranowski, R. ; Thachuk, M. Collision-Induced Alignment Of No+ Drifting In Argon: Calculated Distribution Functions And Microscopic Quadrupole Alignment Parameters. Journal of Chemical Physics 2002, 116, 6605-6613.


Baranowski, R. ; Wagner, B. ; Thachuk, M. Molecular Dynamics Study Of The Collision-Induced Rotational Alignment Of N-2(+) Drifting In Helium. Journal of Chemical Physics 2001, 114, 6662-6671.



Baranowski, R. ; Thachuk, M. Mobilities Of No+ Drifting In Helium: A Molecular Dynamics Study. Journal of Chemical Physics 1999, 110, 11383-11389.



Thachuk, M. ; Chuaqui, C. E. ; LeRoy, R. J. Linewidths And Shifts Of Very Low Temperature Co In He: A Challenge For Theory Or Experiment?. Journal of Chemical Physics 1996, 105, 4005-4014.