Alain St-Amant

Computational and Theoretical Chemistry

  • Position: Professor, Chair
  • Education: Ph.D. (Montréal)
  • Phone: (613) 562-5769
  • Fax: (613) 562-5170
  • E-Mail:Alain.St-Amant@uOttawa.ca

Specific Topics:

Within any quantum mechanical (QM) method, the best way to handle a small molecule is not necessarily the best way to handle a large molecule. Our research focusses on the development of algorithms specifically designed to treat large systems. We are therefore actively working on creating QM methods which scale linearly with system size, as opposed to quadratically, or worse, with conventional ab initio software. Even when linear scaling is achieved, these methods will still be too expensive to model very large systems, such as enzymes. Therefore, for these systems, we are working on approaches which combine sophisticated QM methods with cheaper molecular mechanical (MM) methods, treating the important regions, such as the active site, by QM means, and the rest by MM means. Finally, these algorithmic developments must be implemented within a software package specifically designed for massively parallel computer architectures if we are to have any hope of treating truly large systems within a reasonable amount of time. All this work is done within our own density functional theory program, DeFT.

Recent Publications:

D. Courmier, F. Gardebien, C. Minot, and A. St-Amant, "A Computional Study of the Water-catalyzed Formation of NH2CH2OH" Chem. Phys. Lett. 405, 357 (2005).

D. M. Shaw, A. St-Amant, "Linear Scaling for Density Functional Calculations on Large Molecules with the DeFT Software Package" J. Theor. Comput. Chem. 3, 419 (2004).

E. F. Archibong and A. St-Amant, "An ab initio and Density Functional Study of A13As, A13AsG A1As3, and A1As3G " J. Phys. Chem. A 106, 7390 (2002)

E. F. Archibong, A. St-Amant, S. K. Goh, and D. S. Marynick, "On the Structure and Electron Photodetachment Spectra of Ga3PG and Ga3AsG " Chem. Phys. Lett. 361, 411 (2002).

E. F. Archibong, A. St-Amant, S. K. Goh, and D. S. Marynick, "Structure and Electron Detachment Energies of A13PGand A13P3G" J. Phys. Chem. A 106, 5932 (2002).

E. F. Archibong, A. St-Amant, "Electron Detachment Energies of A1AsG and A1As2G" Chem. Phys. Lett. 355, 249 (2002).

E. F. Archibong, A. St-Amant, "On the Photoelectron Spectrum of Ga2P2G " Chem. Phys. Lett. 330, 199 (2000).

E. F. Archibong and A. St-Amant, "Ab Initio and B3LYP-DFT Calculations of GaPG and GaP2G: the Electron Affinities and Vibrational Frequencies of GaP and GaP2", Chem. Phys. Lett., 316, 151 (2000).

E. F. Archibong and A. St-Amant, "On the Structure of Al2O3 and Photoelectron Spectra of Al2O2G and Al2O3G", J. Phys. Chem. A 103, 1109 (1999).

E. F. Archibong and A. St-Amant, "Molecular Structure of the AlO2 Dimer, Al2O4" J. Phys. Chem. A 102, 6877 (1998).

S.K. Goh, R.T. Gallant, and A. St-Amant, "Towards Linear Scaling for the Fits of the Exchange-Correlation Terms in the LCGTO-DF Method via a Divide-and-Conquer Approach", Int. J. Quantum Chem. 69, 405 (1998).

E. F. Archibong and A. St-Amant, "A Study of Gen- and Gen (n = 2 - 6) Using B3LYP-DFT and CCSD(T) Methods: The Structures and Electron Affinities of Small Germanium Clusters", J. Chem. Phys. 109, 962 (1998).

S.K. Goh, C.P. Sosa, and A. St-Amant, "A Scalable Divide-and-Conquer Algorithm Combining Coarse and Fine Grain Parallelization", Theor. Chem. Acc. 99, 197 (1998).

E. F. Archibong and A. St-Amant, "The Cyclic MO2 (M = Al, Ga) Systems: CCSD(T) and DFT Studies of Their Structures, Harmonic Vibrational Frequencies, and Dissociation Energies", Chem. Phys. Lett. 284, 331 (1998).

S.K. Goh and A. St-Amant, "Improving the Efficiency and Reliability of the Divide-and-Conquer Approach to Constructing the Electronic Density", Chem. Phys. Lett. 274, 429 (1997).

S.K. Goh and A. St-Amant, "Using a Fitted Electronic Density to Improve the Efficiency of a Linear Combination of Gaussian-Type Orbitals Calculation", Chem. Phys. Lett. 264, 9 (1997).

R.T. Gallant and A. St-Amant, "Linear Scaling for the Charge Density Fitting Procedure of the Linear Combination of Gaussian-Type Orbitals Density Functional Method", Chem. Phys. Lett. 256, 569 (1996).

A. St-Amant, "A Gaussian Implementation of Yang's Divide-and-Conquer Density Functional Theory Approach", ACS Symposium Series 629, Chemical Applications of Density-Functional Theory, B.B. Laird, R.B. Ross, and T. Ziegler, Eds., (American Chemical Society, Washington, 1996).

A. St-Amant, "The Study of Biomolecules by Density Functional Methods", in Reviews in Computational Chemistry 7, K.B. Lipkowitz and D.B. Boyd, Eds., (VCH Publishers, New York, 1996).

A. St-Amant, S.K. Goh, and R.T. Gallant, "A Divide-and-Conquer Implementation of the Linear Combination of Gaussian-Type Orbitals Density Functional (LCGTO-DF) Method", in Recent Developments and Applications of Modern Density Functional Theory, J. Seminario, Ed., (Elsevier, Amsterdam, 1996).

A. St-Amant, "Practical Density Functional Approaches in Chemistry and Biochemistry", in Quantum Mechanical Simulation Methods for Studying Biological Systems, D. Bicout and M. Field, Eds., (Springer-Verlag, Berlin, 1996).

A. St-Amant, W.D. Cornell, T.A. Halgren, and P.A. Kollman, "A Study of Geometries, Conformational Energies, Dipole Moments and Electrostatic Potential Fitted Charges Using Density Functional Theory", J. Comput. Chem. 16, 1483 (1995).

Recent Publications by Others Using DeFT:

  1. A.J. Bridgeman, "On the Bonding in pi-Complexes of Borazine", Polyhedron 17, 2279 (1998).
  2. A.J. Bridgeman, "Bonding in the Monochlorides and Dichlorides of Iron and Cobalt", J. Chem. Soc., Dalton Trans., 4765 (1997).
  3. A.J. Bridgeman, "The Shapes of bis(cyclopentadienyl) Complexes of the s-Block Metals", J. Chem. Soc., Dalton Trans., 2887 (1997).
  4. X.P. Long, J.B. Nicholas, M.F. Guest, and R.L. Ornstein, "A Combined Density Functional Theory/Molecular Mechanics Formalism and Its Application to Small Water Clusters", J. Mol. Struct. 412, 121 (1997).
  5. A.J. Bridgeman, "Structure and Bonding of Group 13 Monocarbonyls", J. Chem. Soc., Dalton Trans., 1323 (1997).
  6. P. Fuentealba and Y. Simon-Manso, "Static Dipole Polarizabilities through Density Functional Methods", J. Phys. Chem. A 101, 4231 (1997).
  7. A.J. Bridgeman and C.H. Bridgeman, "Bonding, Bending and the Ground State of CrCl2", Chem. Phys. Lett. 272, 173 (1997).
  8. A. Garcia, E.M. Cruz, C. Sarasola, and J.M. Ugalde, "Performance of Becke's Exchange Functional Fitted for Gaussian Basis Sets", J. Mol. Struct. (THEOCHEM) 363, 279 (1996).
  9. A.J. Bridgeman, "The Electronic Structure of `Linear' Nickel Oxides", J. Chem. Soc., Dalton Trans., 4555 (1996).
  10. A.J. Bridgeman, "On the Electronic Structures and Spectra of NiCl2 and CuCl2", J. Chem. Soc., Dalton Trans., 2601 (1996).
  11. P. Bour and L. Bednarova, "Anharmonic Force Field of Formamide. A Computational Study", J. Phys. Chem. 99, 5961 (1995).
  12. R.W. Williams, J.L. Cheh, A.H. Lowrey, and A.F. Weir, "Effects of Hydration on Scale Factors for ab Initio Force Constants. 9. Methanol", J. Phys. Chem. 99, 5299 (1995).
  13. S. Tobisch and H. Boegel, "Theretical Studies of Organonickel Compounds. I. A Density Functional and Ab Initio HF Study", Int. J. Quantum. Chem. 56, 575 (1995).