Professor Ali Alavi FRS | 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

Evaluation of diffusion mechanisms in NiAl by embedded-atom and first-principles calculations - art. no. 014201

Y Mishin, AY Lozovoi, A Alavi

Physical Review B Condensed Matter and Materials Physics

(2003)

67

014201

(doi: 10.1103/PhysRevB.67.014201)

Structures and thermodynamic phase transitions for oxygen and silver oxide phases on Ag{111}

A Michaelides, M-L Bocquet, P Sautet, A Alavi, DA King

Chemical Physics Letters

(2003)

367

344

(doi: 10.1016/S0009-2614(02)01699-8)

Two interacting electrons in a spherical box: An exact diagonalization study

DC Thompson, A Alavi

Physical Review B Condensed Matter and Materials Physics

(2002)

66

235118

(doi: 10.1103/PhysRevB.66.235118)

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

J Am Chem Soc

(2002)

124

14770

(doi: 10.1021/ja0205885)

Polymers near metal surfaces: Selective adsorption and global conformations

L Delle Site, CF Abrams, A Alavi, K Kremer

Phys Rev Lett

(2002)

89

156103/1

(doi: 10.1103/PhysRevLett.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

(2002)

65

2241091

(doi: 10.1103/physrevb.65.224109)

Evidence for partial dissociation of water on flat MgO(1 0 0) surfaces

YD Kim, RM Lynden-Bell, A Alavi, J Stulz, DW Goodman

Chemical Physics Letters

(2002)

352

318

(doi: 10.1016/S0009-2614(02)00009-X)

The use of XANES and ELNES for the characterisation of stabilised zirconia

DW McComb, S Ostanin, D Vlachos, AJ Craven, MW Finnis, AT Paxton, A Alavi

Materials Research Society Symposium Proceedings

(2002)

699

161

Structures of adsorbed water layers on MgO: an ab initio study

RM Lynden-Bell, L Delle Site, A Alavi

Surface Science

(2002)

496

L1

(doi: 10.1016/s0039-6028(01)01669-7)

What can classical simulators learn from ab initio simulations?

L Delle Site, RM Lyndeb-Bell, A Alavi

Journal of Molecular Liquids

(2002)

98

79

(doi: 10.1016/s0167-7322(01)00311-7)