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Yusuf Hamied Department of Chemistry

 

Professor of Theoretical Chemistry

The work of our group is primarily focused on the electron correlation problem - namely how to compute the correlation energy for an atom, molecule, or even solid, starting from a mean-field (say Hartree-Fock) description of the system. Our approach is to combine quantum chemical ideas with stochastic (Monte Carlo) techniques, which enable us to tackle problems which are very difficult to solve use standard quantum chemical techniques alone.

We are developing Quantum Monte Carlo algorithms adapted for electronic (and more generally Fermionic) problems by working in Slater determinant spaces. The central problem which is encountered is the infamous "Fermion sign problem", which results from electronic wavefunctions having both positive and negative amplitudes. Currently we are working on a novel population dynamics algorithm which propagates walkers in Slater determinant space according to a type of "stochastic cellular automaton" obeying simple rules. The movie on the home page of our research group website shows an evolving population of walkers of positive and negative sign settling on the FCI wavefunction of a nitrogen dimer in a minimal basis - an archetypal multireference system. The remarkable aspect of this dynamics is the spontaneous symmetry breaking caused by annhilation processes, allowing the exact nodal surface of the nitrogen molecule, as expressed by the CI coefficients, molecule to appear. No fixed-node approximation is applied.

Further animations of this method in action can be viewed here.

Publications

Adsorption energies and geometries of phenol on the (111) surface of nickel: An ab initio study
L Delle Site, A Alavi, CF Abrams
– Physical Review B - Condensed Matter and Materials Physics
(2003)
67,
1934061
New insights into ethene epoxidation on two oxidized Ag{111} surfaces
M-L Bocquet, A Michaelides, D Loffreda, P Sautet, A Alavi, DA King
– J Am Chem Soc
(2003)
125,
5620
Identification of general linear relationships between activation energies and enthalpy changes for dissociation reactions at surfaces
A Michaelides, Z-P Liu, CJ Zhang, A Alavi, DA King, P Hu
– J Am Chem Soc
(2003)
125,
3704
Different Surface Chemistries of Water on Ru{0001}:  From Monomer Adsorption to Partially Dissociated Bilayers
A Michaelides, A Alavi, DA King
– Journal of the American Chemical Society
(2003)
125,
2746
Evaluation of diffusion mechanisms in NiAl by embedded-atom and first-principles calculations
Y Mishin, AY Lozovoi, A Alavi
– Physical Review B
(2003)
67,
014201
Structures and thermodynamic phase transitions for oxygen and silver oxide phases on Ag{1 1 1}
A Michaelides, ML Bocquet, P Sautet, A Alavi, DA King
– Chemical Physics Letters
(2003)
367,
344
Two interacting electrons in a spherical box: An exact diagonalization study
DC Thompson, A Alavi
– Physical Review B
(2002)
66,
2351181
Catalytic role of gold in gold-based catalysts: a density functional theory study on the CO oxidation on gold.
Z-P Liu, P Hu, A Alavi
– Journal of the American Chemical Society
(2002)
124,
14770
Polymers near metal surfaces: Selective adsorption and global conformations
L Delle Site, CF Abrams, A Alavi, K Kremer
– Phys Rev Lett
(2002)
89,
156103
Electron energy-loss near-edge shape as a probe to investigate the stabilization of yttria-stabilized zirconia
S Ostanin, AJ Craven, DW McComb, D Vlachos, A Alavi, AT Paxton, MW Finnis
– Physical Review B - Condensed Matter and Materials Physics
(2002)
65,
2241091
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Research Group

Research Interest Group

Telephone number

01223 762877

Email address

asa10@cam.ac.uk