CMSP Seminar Series @ICTP Stasi Room Thursday 23 November 11:30 - M. SULPIZI

[CM Section]

ICTP Seminar Series in Condensed Matter and Statistical Physics
----------------------------------------------------------------------------------------- 


Thursday 23 November at 11:30 a.m.
Luigi Stasi Seminar Room, first floor, ICTP Leonardo building
*********************************************************************

Speaker:
Marialore SULPIZI (Dept. of Physics, Johannes Gutenberg University, 
Mainz,Germany)

Title:
Water Interfaces: Structure and Vibrational Spectroscopy from Ab Initio MD

Abstract:
Ab initio molecular dynamics (MD) simulations represent a versatile 
approach to investigate
the structure and dynamics of water interfaces, especially in the cases 
of heterogeneous
systems where less computationally demanding techniques, such as force 
field approaches
are not easily transferable.

We present here some recent results on the calculation of vibrational 
Sum Frequency
Generation spectra, which employ suitable velocity-velocity correlation 
functions incorporating
the appropriate selection rules [1,2].

We also present a new approach to investigate vibrational energy 
relaxation at water interfaces
from the analysis of ab initio non-equilibrium MD trajectories. We 
follow the energy relaxation
from a locally excited vibrational state using suitable descriptors 
based on vibrational density
of states.

Our method is tested on different water systems, including bulk water 
and fluorite/water interfaces
at different pH and can be used to provide a molecular interpretation of 
2D-IR or 2D-SFG spectra.
In the case of the water/fluorite interface at low pH we find that water 
behaves similarly to bulk
water, while, in the case of high pH, instead, the energy relaxation is 
much slower. A molecular
interpretation of the different time scales is provided.


[1] R Khatib, EHG Backus, M Bonn, MJ Perez-Haro, MP Gaigeot, M Sulpizi, 
Scientific

Reports, 6 (2016)

[2] R. Khatib and M Sulpizi, J. Phys. Chem. Letters, 8 (6), 1310 (2017).**