18.09.2008 17:15 c.t.
Quantum transitions in Lennard-Jones clusters
by Prof. Vladimir Mandelshtam
from University of California, Irvine
Seminarraum Haus 2, 4. Stock (Bunsenstr.)
I will present our most recent numerical results on thermodynamics of
quantum Lennard Jones (LJ) clusters.
The classical LJ(n) clusters had been studied previously and very
extensively, particularly in our group:
J. Chem. Phys. 2006, 124, 20451;
J. Phys. Chem. , 2007, 111, 10284.
The above numerical results demonstrate how complex these systems can be
(even without taking into account the quantum effects), having a number of
structural motifs that are thermodynamically stable for different ranges
of the size n and temperature T.
The quantm effects change the critical parameters (n and T) as we
demonstrated for the case of neon clusters:
J. Chem. Phys. 2005, 122, 154305;
Phys. Rev Lett. 2006, 96, 113401
Our most recent results explore the evolution of the ground state (i.e.,
the zero temperature case) of the LJ(n,L) cluster as a function of its
size n and the de Boer quantum delocalization length L. The corresponding
"phase diagram" that we constructed shows the stability ranges for the
competing structural motifs. An increase of L has an effect similar to
heating and as such may induce structural transformations.
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