Prof. Antonino Marco Saitta [Université Pierre et Marie Curie – Sorbonne, FRANCE]

Title: A new topological approach for transformations of matter

Time: 10:00 - 11:00 AM, Friday, October 28, 2016

Place: Auditorium Room 410, HPSTAR (Shanghai)

Host: Dr. DuckYoung Kim

Abstract:

In this talk I will present the optimized an enhanced sampling and free energy calculation approach we have recently developed in my group, which allows the (ab initio or classical) molecular dynamics simulation of any transformation in condensed matter. The central idea [1] is to combine a new metric, based on so-called Permutation Invariant Vectors, with a powerful enhanced sampling algorithm, metadynamics based on path collective variables. On one hand, the PIV metric allows to track the atom-detailed transition pathway of a generic activated process, with an unprecedented range of applicability spanning, e.g., phase transitions among amorphous and crystalline water ices [2]. On the other hand, path-metadynamics grants statistically precise and reproducible free energy landscapes, albeit within a reach that was limited by the lack of metrics able to discriminate structures irrespective of permutations of identical atoms and molecules.This was a particularly severe problem in the study of amorphous and liquid phases, due to the disordered nature of the material and to the occurrence of diffusion processes. The combination of the latter two methodologies now allows exploiting the best of each world, leading to a new powerful and versatile methodology. The main advantage consists in overcoming the problem of struggling to invent system-taylored, and possibly ineffective, collective variables approximating the transformation coordinate for each different application. As a result, it is now possible to pass from one physical problem (i.e., material and/or process) to another in a seamless way.

Biography of the Speaker:

09/2014 – present : Full Professor at Université Pierre et Marie Curie – Sorbonne

09/2011 – 08/2014 : Associate Professor at Université Pierre et Marie Curie – Sorbonne

09/2000 – 08/2011 : Assistant Professor at Université Pierre et Marie Curie – Sorbonne

11/1997 – 08/2000 : Postdoctoral Researcher at University of Pennsylvania (USA)

Name and address of employer : Université Pierre et Marie Curie – Sorbonne University, 4 Place Jussieu – 75005 Paris (France)

Type of business or sector: Scientific Research in Condensed Matter Physics and Materials Science

Occupation or position held: Professor – Deputy Dean of the Physics Departement

Research sectors: Molecular systems under extreme conditions of pressure, temperature, electric fields, by ab initio theoretical calculations. Reactivity at mineral/solution interfaces.

Selected publications:

1. Pietrucci F.,  Saitta A.M. Formamide reaction network in gas phase and solution via a unified theoretical approach: Toward a reconciliation of different prebiotic scenarios.  PNAS 112, 15030 (2015).

2. Pokrovski G.S., …,  Saitta A.M., et al., Sulfur radical species form gold deposits on Earth. PNAS 112, 13484 (2015).

3. Bove L.E., Gaal R., Raza Z., Ludl A.A., Klotz S., Saitta A.M., Goncharov A.F., Gillet P. Effect of salt on the H-bond symmetrization in ice. PNAS 112, 8216 (2015)

4. Saitta A.M., F Saija, F. Pietrucci, and F. Guyot Ab initio free-energy landscape of Miller-like prebiotic reactions. PNAS 112, E343 (2015)