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Yusuf Hamied Department of Chemistry

 

Professor of Theoretical Chemistry

What we do...

Our theoretical research group uses mathematical and computational techniques to investigate quantum behaviour in the motion of atomic nuclei. We carry out computer simulations which illustrate how quantum mechanics changes the motion of atoms and molecules in chemical reactions and inside liquid water and ice.

Research

Our research investigates how the quantum properties of atomic nuclei affect chemical reaction rates and mechanisms. We develop and apply a wide range of theories and computational techniques, from exact solutions of the Schrödinger equation for small systems, to approximate Feynman path- integral approaches for larger systems.

First-principles calculations of wave functions of chemical reactions

We were the first group to calculate a complete time-dependent wave function that visualizes the entire dynamics of a chemical reaction from approach of the reactants through to scattering of the products into space. This work is done in collaboration with a leading experimental group (R.N. Zare, Stanford) who measure detailed product-scattering patterns that our calculations reproduce and interpret in terms of first-principles quantum mechanics.

Instanton simulations of quantum tunnelling

Instantons arise when Feynman path-integral theory is used to describe quantum tunnelling through barriers; they describe the dominant tunnelling path, which gives an approximate but physically rigorous description of the tunnelling dynamics. We have recently developed and extended instanton theory such that the instantons are represented by a series of beads which can be rapidly strung together to describe quantum tunnelling in complex systems. We are currently applying this method to tunnelling in water clusters (in collaboration with Prof. D.J. Wales), and to proton transfer reactions in solution.

Winding effects at conical intersections

Conical intersections arise when potential energy surfaces intersect. We have found that the nuclear wave functions at such intersections can be unwound, such that contributions from Feynman paths that wind different numbers of times around the intersection can be rigorously separated. This gives rise to quantum interference effects; we are currently investigating how such effects influence the efficiency of relaxation through a conical intersection.

Watch Professor Althorpe discuss his research

Publications

State-to-state reactive scattering using reactant-product decoupling
MT Cvitas, SC Althorpe
– Physica Scripta
(2009)
80,
048115
Quantum wave packet method for state-to-state reactive scattering calculations on AB + CD --> ABC + D reactions.
MT Cvitas, SC Althorpe
– The Journal of Physical Chemistry A
(2009)
113,
4557
Effect of the geometric phase on nuclear dynamics at a conical intersection: Extension of a recent topological approach from one to two coupled surfaces
SC Althorpe, T Stecher, F Bouakline
– The Journal of chemical physics
(2008)
129,
214117
Vibrationally inelastic H + D-2 collisions are forward-scattered
NT Goldberg, J Zhang, K Koszinowski, F Bouakline, SC Althorpe, RN Zare
– Proceedings of the National Academy of Sciences of the United States of America
(2008)
105,
18194
Geometric phase effects in resonance-mediated scattering: H+H2+ on its lowest triplet electronic state
JC Juanes-Marcos, AJC Varandas, SC Althorpe
– J Chem Phys
(2008)
128,
211101
New, unexpected, and dominant mechanisms in the hydrogen exchange reaction.
SJ Greaves, D Murdock, E Wrede, SC Althorpe
– The Journal of chemical physics
(2008)
128,
164306
The Influence of the Geometric Phase on Reaction Dynamics
SC Althorpe, JC Juanes-Marcos, E Wrede
– ADVANCES IN CHEMICAL PHYSICS, VOL 138
(2008)
138,
1
Strong geometric-phase effects in the hydrogen-exchange reaction at high collision energies.
F Bouakline, SC Althorpe, D Peláez Ruiz
– Journal of Chemical Physics
(2008)
128,
124322
Nearside−Farside and Local Angular Momentum Analyses of Time-Independent Scattering Amplitudes for the H + D2 (v i = 0, j i = 0) → HD (v f = 3, j f = 0) + D Reaction †
PDD Monks, JNL Connor, SC Althorpe
– Journal of Physical Chemistry A
(2007)
111,
10302
Differential cross section for the H+D2 →hD (v′ =1, j′ =2,6,10) +D reaction as a function of collision energy
K Koszinowski, NT Goldberg, J Zhang, RN Zare, F Bouakline, SC Althorpe
– Journal of Chemical Physics
(2007)
127,
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Research Group

Research Interest Group

Telephone number

01223 336373

Email address

sca10@cam.ac.uk