Sandro Sorella

E-mail

 sorella (at) sissa.it

Office

 A 307

Web

 http://people.sissa.it/~sorella/

Tel

 +39 040 3787 444

Fax

 +39 040 3787 249

Vita

Sandro Sorella: present Full Professor in Condensed Matter physics, SISSA Trieste, from 2005. associate professor in Condensed Matter physics from 1998. During the period 1990-1991, post doc at ETH-Zurich in the T.M. Rice group. PhD in Condensed Matter, SISSA, Trieste, on December 1989. During the activity in SISSA he has followed about ten PhD students. About half of them have been hired in important international institutions.
Relevant results have been obtained for the so called ”Mott insulators” where some important properties of the excitation spectrum have been clearly established. His contribution to the development of novel numerical techniques has been widely recognized with a strong impact to the scientific community. The most recent numerical techniques have clarified important aspects of the theoretical problems posed by the recent experiment on high critical temperature superconductors. Recently much attention has been devoted to the electronic simulation of realistic systems by means of Quantum Monte Carlo, and in particular to the study of several carbon based compounds of particular chemical and physical interest.

Research

The scientific activity is mainly devoted to the study of strongly correlated electron systems by means of numerical simulations based on quantum Monte Carlo. The main motivation is to shed lights on phenomena where simple mean-field treatments are inadequate and often lead to wrong predictions. On the other hand well established numerical techniques allow us to clarify the effect of the strong electron correlation in simple model systems, where, so far, no analytical treatment is able to provide a reliable solution. In this respect it is worth to mention that the first evidence that strong correlation may explain the High Temperature superconductivity observed in cuprates , was given by the numerical simulation of the t-J model (Ts, early ‘98) . Other phenomena, like spin liquid behavior and the Mott physics, observed in several materials , are becoming a challenge for numerical methods, requiring a very accurate numerical solution of model systems. This is also particularly important in the recent years in view of the tremendous experimental progress, based on ultracold atoms in optical lattices .
In this respect our scientific directions in the near future are the following:

  1. from one side we are developing a new tool for electronic structure calculation based on quantum Monte Carlo (the TurboRVB code), that allows to describe the electron correlation by first principle simulation on real materials. In particular it is possible to study superconductivity in cuprate materials (like CaCuO2) or the recent Iron based superconductors (BaFe2As2). This is at present our most ambitious project.. Similarly we plan to push the efficiency of the Monte Carlo simulation for an accurate determination of the phase diagram of graphene, water and hydrogen.
  2. On the other hand, we believe that there are several important issues that needs to be clarified by means of numerical simulation of strongly correlated models.The tendency to charge segregation close to a Mott insulator and its role in enhancing the superconducting temperature has not been clarified yet.Spin liquid behavior, namely absence of any broken symmetry in the ground state of a spin-1/2 electronic system, has not been well established by convincing numerical calculations, though, recently, some exciting result was obtained in the honeycomb lattice (Muramatsu, Nature 2010). We plan to push further the numerical evidence with a more efficient numerical Monte Carlo technique.
  3. Finally from the methodological point of view it is important to extend the very successul ground state Monte Carlo technique to finite temperature, because so far, no reliable technique is available to estimate the critical superconducting temperature, in a strongly correlated system, e.g. the Hubbard model.

Publications

  1. ”Magnetism and superconductivity in the t-t ‘-J model”, L. Spanu, M. Lugas, F. Becca, and S. Sorella, Phys. Rev. B  77, 024510 (2008).
  2. ”Stable liquid hydrogen at high pressure by a novel ab initio molecular-dynamics calculation” Attaccalite C, Sorella S , Phys. Rev. Lett. 100, 114501 (2008).
  3. ”Mott transition in bosonic systems: Insights from the variational approach”, Capello M, Becca F, Fabrizio M, and S. Sorella, Phys. Rev. B 77, 144517 (2008).
  4. ”Role of backflow correlations for the nonmagnetic phase of the t-t’ Hubbard model”, L.F. Tocchio, F. Becca, A. Parola, and S. Sorella, Phys. Rev. B 78, 041101 (2008).
  5. ”Dissecting the hydrogen bond: A quantum Monte Carlo approach”, F. Sterpone, L. Spanu, L. Ferraro, and S. Sorella, Jour. of Chem. Theor. and Comp. 4, 1428 (2008).
  6. ”Exact Jastrow-Slater wave function for the one-dimensional Luttinger model”, B. Tayo, S. Sorella, Phys. Rev. B 78, 115117 (2008).
  7. ”Molecular hydrogen adsorbed on benzene: Insights from a quantum Monte Carlo study”, Beaudet TD, Casula M, Kim J, S. Sorella and R. Martin, Jour. of Chem. Phys. 129, 164711 (2008).
  8. Spin- 1/2 Heisenberg model on the anisotropic triangular lattice: From magnetism to a one-dimensional spin liquid”, Dariush Heidarian, Sandro Sorella, and Federico Becca, Phys. Rev. B 80, 012404 (2009).
  9. “ Resonating Valence Bond wave function with molecular orbitals: application to first row atoms”, M. Marchi, S. Azadi and Sandro Sorella, J. Chem. Phys. 131, 154116 (2009).
  10. “Nature and strength of the chemical bond in graphite” Leonardo Spanu, Sandro Sorella, and Giulia Galli Phys. Rev. Lett. 103, 196401 (2009).
  11. “Size consistent variational approaches to non local pseudopotentials, standard and lattice regularized diffusion Monte Carlo revisited”, Michele Casula, Saverio Moroni, Sandro Sorella and Claudia Filippi, J. Chem. Phys. 132, 154113 (2010).
  12. “Systematically convergent method for accurate total energy calculations with localized atomic orbitals” S. Azadi, C. Cavazzoni, and S. Sorella Phys. Rev. B 82, 125112 (2010).
  13. S. Sorella, M. Casula, L. Spanu, and A. Dal Corso,  “Ab initio calculations for the β-tin diamond transition in silicon: Comparing theories with experiments”,  .Phys. Rev. B 83, 075119 (2011).