Organisers

• Matthieu Micoulaut (Université Paris 6)
• Normand Mousseau (Université de Montréal)
• Alfredo Pasquarello (EPFL, Institut de théorie des phénomènes physiques)

Supports

 CECAM

 COST - MolSimu

Description

Scientific background

The understanding of glasses and the nature of the glass
transition remains one of the greatest challenges in condensed
matter science. It is not surprising, therefore, that many
different communities have studied the problem, coming from
engineering, condensed matter physics and statistical
mechanics. While there have been many conferences addressing
one approach or the other, there have been very few attempts at
bringing together the leading practitioners from all these
areas in order to establish a real dialogue. Glasses meet
glasses intends to do just that. We propose to invite
theoreticians from all these fields in an environment where
discussion can take place, providing a much needed exchange of
ideas at a time when many fields have progressed on their own.
Selected experimentalists are also invited to contribute to the
discussion.
Indeed, important achievements [1] have been realized due,
in part, to the increased power of computational resources.
Both Molecular Dynamics (MD) simulations and ab initio methods
provide a good basis to describe relaxation and kinetic
phenomena [2], structures of glass-forming liquids [3],
vibrational and structural properties of amorphous materials
[4]. On the other hand, much of the behaviour of glasses is
independent of the details of the inter-atomic forces and
approaches have been proposed that rely either on hydrodynamics
[5], or bond distance constraints [6], lattice Hamiltonians
[7], kinetic constrained models [8] with sometimes restricted
areas of applicability such as the high temperature/low
viscosity regimes or the fully connected glass network at low
temperature.
While fragile glass forming liquids with no directive
(covalent) interactions have been studied in the context of
glass transition for some time, simulations on typical network
glasses such as oxide or chalcogenide glasses have received
attention only recently [9]. Work related to glass transition
is regularly reported in high impact journals and the
description in terms of the (complex) underlying energy
landscape [10] and the way connectedness of the network
influences the nature of dynamics is becoming more and more
accurate.
Numerous specific conferences on glasses, glass transition
or non-crystalline materials have taken place over the years
with isolated communities that rarely exchange ideas, concepts
and related experiments. While progress has been quite
spectacular, particularly in the last few years, many questions
remain unanswered with some recently developed concepts
appearing almost incompatible with each other.
We therefore believe that there is a need for a suitably
designed CECAM workshop that can offer the opportunity to make
an assessment of the current theoretical developments in this
field from across the board, along with recent experiments
performed in this context (Hyper-Raman, isotopic substitution
techniques and inelastic neutron scattering, modulated
differential scanning calorimetry,.).

Scientific Objectives

Motivations and objectives

Glass science is a huge area in which the motivations to
the theoretical study of the properties of glasses depend very
much on the nature of the investigated system: liquid or solid,
weak or strong interacting, equilibrated or out of equilibrium,
etc. Beyond these extreme situations where theory offers
sometimes a precise description are found a variety of systems
for which the theoretical effort for a complete understanding
is still lacking. To address these issues, it is essential to
bring together researchers coming from almost isolated
communities supercooled liquids, ageing, covalent glass
formers, thermodynamics, dynamics below the glass transition
temperature, jamming ,etc.
The aim of this workshop is therefore two-fold: 1) An
objective in direction of the attendees: they will have the
opportunity to learn about recent theoretical methodologies by
leading groups in the field with broad overviews of the latest
developments. 2) an objective in direction of the speakers from
different communities who will exchange and discuss on ideas
and concepts, tools and experimental results.
This should lead to an increased interaction in the field
and potential new developments are expected to emerge from the
discussions at this workshop. In order to allow these
interactions to take place efficiently, a certain format of the
sessions of the conference has been chosen (see below).

Format

We foresee about 25 speakers for this workshop with a schedule
that will allow extensive discussions so that, in the words of
one invited participants, it is possible to "nudge people
outside of their comfort zone" and achieve a real discussion
and debate. Specifically, we plan to have 6 sessions of half a
day each with talks of 30 minutes followed by a discussion of
at least 15 minutes. However, the duration of the after-talk
discussion is planed to be adaptative, i.e. additional time can
be used after any talk if needed. This should lead to an
approximate ratio of 1:1 between the formal talk and the
discussion.
The overall organization of the sessions should be as follows:
Session 1: Structure I: classical
Session 2: Spin glass approaches and ageing
Session 3: Topological based approaches
Session 4: Hydrodynamic theories and jamming
Session 5 : Structure II: Ab initio methods
Session 6 : Frontiers in glass science and Round Table.

The total number of participants should be around 25.
Throughout the workshop, we will dedicate considerable time to
discussions.

References

[1]