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Professor Ali Alavi FRS

Portrait of asa10

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 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.

 

Teaching

 

Please click on: http://www-alavi.ch.cam.ac.uk/teaching

 

Publications

 

Please click on: http://www-alavi.ch.cam.ac.uk/publications

Publications

Krylov-Projected Quantum Monte Carlo Method.
NS Blunt, A Alavi, GH Booth – Phys Rev Lett (2015) 115, 050603
Semi-stochastic full configuration interaction quantum Monte Carlo: Developments and application.
NS Blunt, SD Smart, JA Kersten, JS Spencer, GH Booth, A Alavi – The Journal of chemical physics (2015) 142, 184107
Theory and Practice: Bulk Synthesis of C 3 B and its H 2 - and Li-Storage Capacity
TC King, PD Matthews, H Glass, JA Cormack, JP Holgado, M Leskes, JM Griffin, OA Scherman, PD Barker, CP Grey, SE Dutton, RM Lambert, G Tustin, A Alavi, DS Wright – Angew Chem Int Ed Engl (2015) 54, 5919
Insights into the structure of many-electron wave functions of Mott-insulating antiferromagnets: The three-band Hubbard model in full configuration interaction quantum Monte Carlo
LR Schwarz, GH Booth, GH Booth, A Alavi, A Alavi – Physical Review B - Condensed Matter and Materials Physics (2015) 91, ARTN 045139
Accurate Ab initio calculation of ionization potentials of the first-row transition metals with the configuration-interaction quantum Monte Carlo technique.
RE Thomas, GH Booth, A Alavi – Phys Rev Lett (2015) 114, 033001
Analytic nuclear forces and molecular properties from full configuration interaction quantum Monte Carlo.
RE Thomas, D Opalka, C Overy, PJ Knowles, A Alavi, GH Booth – The Journal of chemical physics (2015) 143, 054108
Unbiased reduced density matrices and electronic properties from full configuration interaction quantum Monte Carlo
C Overy, GH Booth, NS Blunt, JJ Shepherd, D Cleland, A Alavi – The Journal of chemical physics (2014) 141, 244117
Linear-scaling and parallelisable algorithms for stochastic quantum chemistry
GH Booth, SD Smart, A Alavi – Molecular Physics (2014) 112, 1855
Linear-scaling and parallelisable algorithms for stochastic quantum chemistry
GH Booth, GH Booth, SD Smart, A Alavi – Molecular Physics (2014) 112, 1855
Symmetry breaking and broken ergodicity in full configuration interaction quantum Monte Carlo
RE Thomas, C Overy, GH Booth, A Alavi – Journal of Chemical Theory and Computation (2014) 10, 1915
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Research Group

Research Interest Group

Telephone number

01223 762877

Email address

asa10@cam.ac.uk