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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

Calculating splittings between energy levels of different symmetry using path-integral methods.
E Mátyus, SC Althorpe
– The Journal of Chemical Physics
(2016)
144,
114109
Locating Instantons in Calculations of Tunneling Splittings: The Test Case of Malonaldehyde
MT Cvitaš, SC Althorpe
– Journal of Chemical Theory and Computation
(2016)
12,
787
Rovibrational transitions of the methane-water dimer from intermolecular quantum dynamical computations
J Sarka, AG Császár, SC Althorpe, DJ Wales, E Mátyus
– Phys Chem Chem Phys
(2016)
18,
22816
Fundamentals: general discussion
SC Althorpe, V Beniwal, PG Bolhuis, J Brandão, DC Clary, J Ellis, W Fang, DR Glowacki, TJH Hele, H Jónsson, J Kästner, N Makri, DE Manolopoulos, LK McKemmish, G Menzl, TF Miller, WH Miller, E Pollak, S Rampino, JO Richardson, M Richter, P Roy Chowdhury, D Shalashilin, J Tennyson, R Welsch
– Faraday discussions
(2016)
195,
139
Non-adiabatic reactions: general discussion.
SC Althorpe, N Ananth, G Angulo, RD Astumian, V Beniwal, J Blumberger, PG Bolhuis, B Ensing, DR Glowacki, S Habershon, S Hammes-Schiffer, TJH Hele, N Makri, DE Manolopoulos, LK McKemmish, TF Miller, WH Miller, AJ Mulholland, T Nekipelova, E Pollak, JO Richardson, M Richter, P Roy Chowdhury, D Shalashilin, R Szabla
– Faraday discussions
(2016)
195,
311
Differential Cross Sections for the H + D2 → HD(v′ = 3, j′ = 4–10) + D Reaction above the Conical Intersection
H Gao, M Sneha, F Bouakline, SC Althorpe, RN Zare
– J Phys Chem A
(2015)
119,
12036
Communication: Relation of centroid molecular dynamics and ring-polymer molecular dynamics to exact quantum dynamics.
TJH Hele, MJ Willatt, A Muolo, SC Althorpe
– The Journal of Chemical Physics
(2015)
142,
191101
Boltzmann-conserving classical dynamics in quantum time-correlation functions: "Matsubara dynamics"
TJH Hele, MJ Willatt, A Muolo, SC Althorpe
– The Journal of Chemical Physics
(2015)
142,
134103
Which Is Better at Predicting Quantum-Tunneling Rates: Quantum Transition-State Theory or Free-Energy Instanton Theory?
Y Zhang, T Stecher, MT Cvitaš, SC Althorpe
– The Journal of Physical Chemistry Letters
(2014)
5,
3976
Shallow-tunnelling correction factor for use with Wigner-Eyring transition-state theory.
Y Zhang, JB Rommel, MT Cvitaš, SC Althorpe
– Physical chemistry chemical physics : PCCP
(2014)
16,
24292
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Research Group

Research Interest Group

Telephone number

01223 336373

Email address

sca10@cam.ac.uk