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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

Mean-field Matsubara dynamics: analysis of path-integral curvature effects in rovibrational spectra
SC Althorpe, G Trenins
– J Chem Phys
(2018)
149,
014102
Tunneling splittings from path-integral molecular dynamics using a Langevin thermostat.
CL Vaillant, DJ Wales, SC Althorpe
– J Chem Phys
(2018)
148,
234102
Approximating Matsubara dynamics using the planetary model: tests on liquid water and ice
MJ Willatt, M Ceriotti, SC Althorpe
– J Chem Phys
(2018)
148,
102336
Path Integral Energy Landscapes for Water Dimer
CL Vaillant, SC Althorpe, DJ Wales
– J Chem Theory Comput
(2018)
15,
33
Application to large systems: General discussion
S Althorpe, G Angulo, RD Astumian, V Beniwal, PG Bolhuis, J Brandão, J Ellis, W Fang, DR Glowacki, S Hammes-Schiffer, TJH Hele, H Jónsson, T Lelièvre, N Makri, D Manolopoulos, AM Mebel, G Menzl, TF Miller, M Parrinello, PM Piaggi, E Pollak, P Roy Chowdhury, E Sanz, D Shalashilin, E Skúlason, R Spezia, S Taraphder
– Faraday Discuss
(2016)
195,
671
Non-equilibrium dynamics from RPMD and CMD
R Welsch, K Song, Q Shi, SC Althorpe, TF Miller
– Journal of Chemical Physics
(2016)
145,
204118
Quantum Tunneling Rates of Gas-Phase Reactions from On-the-Fly Instanton Calculations
AN Beyer, JO Richardson, PJ Knowles, J Rommel, SC Althorpe
– The Journal of Physical Chemistry Letters
(2016)
7,
4374
An alternative derivation of ring-polymer molecular dynamics transition-state theory.
TJH Hele, SC Althorpe
– J Chem Phys
(2016)
144,
174107
Concerted hydrogen-bond breaking by quantum tunneling in the water hexamer prism.
JO Richardson, C Pérez, S Lobsiger, AA Reid, B Temelso, GC Shields, Z Kisiel, DJ Wales, BH Pate, SC Althorpe
– Science (New York, N.Y.)
(2016)
351,
1310
Quantum tunneling splittings from path-integral molecular dynamics.
E Mátyus, DJ Wales, SC Althorpe
– J Chem Phys
(2016)
144,
114108
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Research Group

Research Interest Group

Telephone number

01223 336373

Email address

sca10@cam.ac.uk