Statistical Mechanics Conference

106th Statistical Mechanics Conference

Sunday, December 18, 2011 at 08:00am -

106th Statistical Mechanics Conference Program
106th List of invited talks and abstracts
106th SMC short talk schedule
106th SMC presenatation of talks
Guests of honor poems

 LIST OF SPEAKERS, TITLES AND ABSTRACTS

Douglas Abraham, University of Oxford
"Strips, Bubbles and Interfere Structure"
Abstract: New results which are inspired by the ideas of Michael Fisher and Ben Widom will be described for the magnetization profile of the planar Ising model with strip geometry and for interface structure. These problems are related to determining the sub-critical pair correlation function, which is given a new interpretation in terms of the Fisher droplet model and one of Fisher's definitions of surface tension.

Amnon Aharony, Tel Aviv University
"Superconducting fluctuations in proximity bilayers"
Abstract: Consider bilayer rings, made of a superconducting and a normal metal adjacent rings. Although the proximity effect reduces the superconducting transition temperature, the superconducting fluctuations remain strong, generating a persistent current in the disordered phase. Although one can describe this problem with a Ginzburg-Landau-like theory, the Ginzburg criterion raises new questions which will be discussed.

Neil Ashcroft, Cornell University
"The Statistical Physics of Dense Hydrogen at the Three-Quarter Century Mark"
Abstract:The statistical physics of N charged spin 1/2 Fermions in a uniform compensating background of volume V (N, V macroscopic) is well developed. Less so is the problem where co-occupying V is also a sign reversed system with quite disparate masses, identical in form and fully coupled to the first. When the more massive system represents nuclei, the ensuing quantum problem was first written down by Dirac. Some six years later, in 1935, Wigner and Huntington approximated the case for atomic number unity (hydrogen) and predicted that at low temperatures, and high compression, the known proton paired insulator could be induced to take up a metallic state. Either as a crystal or a liquid the ensuing highly quantum system is now predicted to have notable orderings (to be elucidated) principally electronic but also nuclear, especially for the heavier Bosonic deuterium. The last 75 years have seen very sustained theoretical and experimental efforts on dense hydrogen, and more recently on hydrogen rich binary systems. And as of this writing a report has just appeared [*] of the attainment, by static compressive means, of a conducting state of hydrogen.
[*] M.I.Eremets and I.A.Troyan, Nature Materials, November 13 (2011)

David Brydges, University of British Columbia, Canada
"The Mayer and Virial Expansions"
Abstract: I will review these expansions for the case of the hard sphere gas, explain why they are useful and why the existing estimates on the radius of convergence of the Virial expansion can probably be greatly improved.

Gunduz Caginalp, University of Pittsburgh
"Phase Field Models with Anisotropy and Non-local Interactions"
Abstract: Two phase field models involving detailed anisotropy will be discussed. One is derived from the higher order terms in a Fourier expansion. Combinatorial identities and asymptotic analysis yield the Gibbs-Thomson-Herring condition that relates the temperature at the interface between phases to the velocity and the anisotropic surface tension. The other allows for non-local interactions in addition to anisotropy. Using differential geometry techniques we derive mathematically elegant expressions that generalize the classical Gibbs-Thomson-Herring interface conditions in arbitrary spatial dimensions. These results are joint work with Xinfu Chen and Emre Esenturk.

  1. Anisotropic Phase Field Equations of Arbitrary Order, (with Emre Esenturk) Discrete and Continuous Dynamical Systems, Series S 4, 311 - 350 (2011).
  2. Interface condition for a phase field model with anisotropic and non-local interactions, The Archive for Rational Mechanics and Analysis (with Xinfu Chen and E. Esenturk) 202, 349-372 (2011) .
  3. A phase field model with non-local and anisotropic potential, (with Xinfu Chen and E. Esenturk) Modelling and Simulation in Materials Science and Engineering 19, (2011).
Eytan Domany, Weizmann Institute
"Complex dynamics of transcriptional response: how do cells get on the fast lane?"
Abstract: n response to external stimuli, cells adjust their behavior to a changing environment - for example, they start to divide or migrate. In order to perform these actions, the protein content of the cell must change. To accomplish this, a cell must modify the levels at which the genes that code for these proteins are transcribed. These transcriptional responses to extracellular stimuli are regulated by tuning the rates of both transcript production and degradation. I present here the results of an experimental study that uses a very simple theoretical model to infer dynamics of RNA production and degradation from measurements of the transcriptome, and to elucidate the operational strategy behind this dynamics.
Our main surprising findings were: a. in general one cannot infer the time-dependent RNA production profiles from measuring mRNA dynamics; b. mRNA degradation exhibits a controlled, transcript dependent temporal variation and c. production of many transcripts is characterized by a large dynamic range, which allow these genes to exhibit an unexpectedly strong transient "production overshoot", thereby accelerating their induction.
A serious attempt will be made to present these results in a way that is understandable to a general Physics audience.
A. Zeisel, W. Koestler et al, Molecular Systems Biology 7, 529 (Sept 13, 2011) http://www.nature.com/msb/journal/v7/n1/full/msb201162.html

Paul Federbush, University of Michigan
"Asymptotic Expansions for ?d(p) of the Monomer-Dimer Problem"
Abstract: We find (so far formal, but certainly true) expansions for ?d(p) of the monomer dimer problem.There is an expansion in powers of 1/d, but the expansion in powers of p is most promising. Terms in the expansion have been computed through power p6 in general dimension, but power seven in dimension two. We have some new rigorous bounds on ?d(p), and a rigorous proof of convergence of our expansion for small enough p. Some of this work was joint with Shmuel Friedland.

Daniel S. Fisher, Stanford University
"Genomic redundancy and evolutionary dynamics"

Matthew P. A. Fisher, University of California, Santa Barbara
"Non-Fermi liquid phases for 2d itinerant electrons"
Abstract: A principle roadblock impeding progress in disentangling the physics of some strongly correlated materials such as the high temperature superconductors is arguably our inability to access quantum ground states of conducting electrons that are qualitatively distinct from a conventional Fermi-liquid metal. Overcoming this obstruction is of paramount importance, indispensable in explaining the "strange metal" phase observed in these materials. I will describe one path that might be fruitful in constructing such putative non-Fermi liquid phases.

Michael E. Fisher, University of Maryland
"COUNTER-EXAMPLES: Charms, Cautions, and Cognition"
Abstract: The talk will discuss informally the charm and attractions of counter-examples in theoretical science, some of the cautions to be borne in mind, and their sometimes valuable contributions in providing true insight. Examples from the speaker's long-ago work will be cited.
  1. MEF and I.J. Zucker, "On a Non-linear Differential Equation for the Zero-point. Energies of the Rare Gas Solids," Proc. Camb. Phil. Soc. 57 (1961) 107-104.
  2. MEF, "The Excluded Volume Problem," Faraday Soc. Discuss. No.26, "Macromolecules"(Leeds, 1958).
  3. MEF and M.F. Sykes, "Excluded-Volume Problem and the Ising Model of Ferromagnetism," Phys. Rev . 114 (1959) 45-58.
  4. MEF, "On Discontinuity of the Pressure," Commun. Math. Phys. 26 (1972) 6-14.
  5. G.W. Milton, "Continuum Fluids with a Discontinuity in the Pressure," J. Stat. Phys. 32 (1983) 413-438.
Martin Fraas, Technion Israel Institute of Technoology
Title: On a definition of current in Markovian open quantum systems
Abstract: The (full) Hamiltonian of an open quantum system is not a property of the system alone. And the notion of energy of the system becomes ambiguous. In the Markovian framework this is manifested in a certain gauge invariance of generators of the evolution. I will exploit it in order to define a gauge invariant current operator, give it properties and discuss when the construction is applicable. This is a join work with Y.~Avron and G.M. Graf.

William Gelbart, University of California, Los Angeles
"Self-assembly of RNA Viruses"
Abstract: The simplest viruses are made up of only two kinds of molecules a single copy of the RNA genome, and 60 or 180 copies of the capsid protein. Fully infectious samples of them can be reconstituted from these purified components in buffer solution. In this talk I discuss theoretical and experimental investigations of the physical aspects of RNA genomes, capsid proteins, and their interactions, in the context of understanding the spontaneous self-assembly process leading to the formation of infectious viruses. This talk is dedicated to Jon Widom, my good friend of many years from whom I learned so much about virtually every aspect of our work on DNA, nucleosomes, RNA, and viruses.

Giambattista Giacomin, Universite Paris 7
"Synchronization of active and inactive rotators"
Abstract: I will present and discuss some recent results on the long time behavior of the Fokker-Planck PDEs that arise in the study of systems of (infinitely many) noisy interacting oscillators. Each oscillator, or rotator, is under the effect of deterministic and stochastic (Brownian type) forces. In the particular case of the Kuramoto synchronization model the deterministic force is a constant, that may vary from one oscillator to another (the choice is random and it can be viewed as a quenched disorder), while in general the force depends on the phase of the oscillators (active rotator model). I will present results for weak disorder andor weak active dynamics that show that the system synchronizes, above a critical interaction threshold, around a phase that rotates with a speed that can be explicitly (and sharply) estimated.

Alexander Grosberg, New York University
"From topology to statistical mechanics of ring polymers to genome folding"

David Huse, Princeton University
"Spin transport in an ultracold atomic Fermi gas"

Kevin Jensen, Naval Research Laboratory
"A Comprehensive Approach to Electron Emission Theory"
Abstract: Several methods are used to create electron beams, and they are in practice attended to by an equivalent number of theoretical models. A more general formulation of all is possible when approached from a distribution function viewpoint, allowing the commonality between thermal, tunneling, photoexcited, and secondary models to be made apparent. A methodology is presented and its extension to treat the more interesting intermediate regimes described. The account keeps in sight other factors intensely important to describing beams, specifically the effect of emitted charge on subsequent emission (space charge) and the inherent spreading of the beam (emittance).

Michael Kiessling, Rutgers University
"Order and Chaos in some Trigonometric Series"
Abstract: I will discuss a one-parameter family of summable sine series which show an interesting complex behavior which changes with the parameter.

Leonid Koralov, University of Maryland
"Polymer measures and branching diffusions"
Abstract: We study two problems related by a common set of techniques. In the first problem, we consider a model for the distribution of a long homopolymer in a potential field. For various values of the temperature, including those at or near the critical value, we consider the limiting behavior of the polymer when its size tends to infinity.
In the second problem, we investigate the long-time evolution of branching diffusion processes in inhomogeneous media. The qualitative behavior of the processes depends on the intensity of the branching. In the super-critical case, we describe the asymptotics of the number of particles in domains that may depend on time and describe the growth of the region containing the particles.

Jorge Kurchan, Ecole Superieure de Physique
Coauthors: C Perez-Espigares and A Kolton
Title: An infinite family of generalizations of the second law
Abstract: The probability distribution function for an out of equilibrium system may sometimes be approximated by a physically motivated 'trial' distribution. A particularly interesting case is when a driven system (e.g. active matter) is approximated by a thermodynamic one. We show here that every set of trial distributions yields an inequality playing the role of a generalization of the Second Law. The better the approximation, the more constraining the inequality becomes: this suggests a criterion for its accuracy, as well as an optimization procedure that may be implemented numerically and even experimentally.

James Langer, University of California, Santa Barbara
"Shear-Transformation-Zone Theory of Glassy Diffusion, Stretched Exponentials, and the Stokes-Einstein Relation"
Abstract: The success of the shear-transformation-zone (STZ) theory in accounting for broadly peaked, frequency-dependent, glassy viscoelastic response functions is based on the theory's first-principles prediction of a wide range of internal STZ transition rates. I propose that the STZ's are the dynamic heterogeneities frequently invoked to explain Stokes-Einstein violations and stretched-exponential relaxation in glass-forming materials. I find that, to be consistent with observations of Fickian diffusion near Tg, an STZ-based diffusion theory must include cascades of correlated events, but that the temperature dependence of the Stokes-Einstein ratio is determined at least in part by an STZ-induced enhancement of the viscosity. Stretched-exponential relaxation of density fluctuations emerges from the same distribution of STZ transition rates that predicts the viscoelastic behavior.
*arXiv: 1108.2738 ; ** E. Bouchbinder and JSL, PRL 106,148301

Yan Levin, Instituto de Fisica UFRGS, Brazil
"Statistical Mechanics of Systems with Long-Range Interactions"
Abstract: Systems with long-range forces behave very differently from those in which particles interact through short-range potentials. For systems with short-range forces, for arbitrary initial conditions, the final stationary state corresponds to the thermodynamic equilibrium and can be described equivalently by either a microcanonical, canonical, or a grand-canonical ensemble. On the other hand, for systems with unscreened long-range interactions, equivalence between ensembles breaks down. In a microcanonical ensemble - in thermodynamic limit - such Hamiltonian systems do not evolve to the usual Maxwell-Boltzmann equilibrium, but become trapped in a non-ergodic stationary state which explicitly depends on the initial particle distribution. In this talk, a theoretical framework will be presented which allows us to obtain the final stationary state achieved by systems with long-range interactions. The theory is able to quantitatively predict both the density and the velocity distributions in the final stationary state, without any adjustable parameters [1,2,3].
  1. Y. Levin, R. Pakter and T. N. Telles, Phys. Rev. Lett. 100, 040604 (2008).
  2. Y. Levin, R. Pakter, and F.B. Rizzato, Phys. Rev. E 78, 021130 (2008); T. N. Teles, Y. Levin, and R. Pakter, Mon. Not. R. Astron. Soc. 417, L21 (2011).
  3. R. Pakter, and Y. Levin, Phys. Rev. Lett. 106, 200603 (2011).

Elliott Lieb, Princeton University
"Possible Lattice Distortion in the Hubbard Model for Graphene"
Coauthor(s): R. Frank
Abstract:The Hubbard model on the honeycomb lattice is a well known model for graphene. Equally well known is the Peierls type of instability of the lattice bond lengths. In the context of these two approximations we ask and answer the question of the possible lattice distortions for graphene in zero magnetic field. The answer is that in the thermodynamic limit only periodic, reflection-symmetric distortions are allowed and these have at most 6 atoms per unit cell as compared to two atoms for the undistorted lattice.

Andrea J. Liu, University of Pennsylvania
"Criticality and the jamming transition"

Satya Majumdar, CNRS/Universite Paris-Sud
"Vicious Walkers, Random Matrices and 2-d Yang-Mills theory"

David Mukamel, The Weizmann Institute
"On the steady state of particle-nonconserving driven models"
Abstract: The effect of particle-nonconserving processes on the steady state of driven diffusive systems will be discussed. It is shown that in the limit of slow nonconserving processes the large deviations function of the overall density can be computed given known properties of the steady state of the conserving model. This enables one to compute phase diagrams and to define a nonequilibrium chemical potential which unlike in the equilibrium case, is dynamics dependent and can show negative compressibility. Correspondence with equilibrium systems with long-range interactions is pointed out. The approach is demonstrated for the ABC model, a driven model exhibiting phase separation in one dimension.

Alex Neimark, Rutgers University
"Breathing Crystals: Adsorption-Induced Deformation and Structural Transitions in Metal-Organic Frameworks"
Abstract: Phenomenon of adsorption-induced deformation attracted recently a considerable attention owing to its relevance to practical problems of mechanical stability and integrity of novel nanoporous materials and their adsorption properties. Guest molecules adsorbed in nanopores cause a substantial stress in the host matrix leading to its contraction or swelling depending on the specifics of host-guest interactions. Although various experimental manifestations of adsorption-induced deformation have been known for a long time, a rigorous theoretical description of this phenomenon is lacking. I will present a general thermodynamic approach to predicting adsorption stress and respective deformation in various microporous and mesoporous materials based on molecular models of adsorption within elastic nanoscale confinements [1-9]. Click here for complete abstract.

David R. Nelson, Harvard University
"Dislocation Mediated Elongation of Bacteria"
Abstract: Recent experiments have revealed a remarkable growth mechanism for rod-shaped bacteria: specialized proteins associated with cell wall elongation move at constant velocity in clockwise and counterclockwise directions on circles around the cell circumference (E. Garner et. al, Science 2011). We argue that this machinery attaches to dislocations in the ordered peptidoglycan cell wall, and study theoretically the dynamics of these interacting defects on the surface of a cylinder. Unlike the dislocations typical in materials science, the motion is predominantly climb (glycan strand extension) instead of glide. The activated motion of these dislocations and the resulting dynamics within a simple kinetic model show surprising effects arising from the cylindrical geometry, with important implications for bacterial growth. *Work done in collaboration with Ariel Amir

Allon Percus, Claremont Graduate University
"The Peculiar Phase Structure of Random Graph Bisection"
Abstract: The phase structure of mincut graph bisection displays certain familiar properties when considered over sparse random graphs, but also some surprises. It is known that when the mean degree is below the critical value of 2 log 2, the bisection width (or cutsize) is zero with high probability. We study how the minimum bisection width increases with mean degree above this critical threshold, finding an analytical upper bound that improves considerably upon previous bounds. Combined with recent results on expander graphs, our bound suggests the unusual scenario that random graph bisection is replica symmetric up to and beyond the critical threshold, with a replica symmetry breaking transition possibly taking place above the threshold. An intriguing algorithmic consequence is that although the problem is NP-hard, we can conceivably find near-optimal bisection widths (whose ratio to the optimal value approaches 1 asymptotically) in polynomial time for typical instances near the phase transition.
This is joint work with Gabriel Istrate, Bruno Goncalves, Robert Sumi and Stefan Boettcher.

Jerome Percus, New York University
"A Random Walk to Fundamental Measure Theory"

Charles S. Peskin, New York University
"A Cell Migration Model with Shock-like Discontinuities"
During the development of the cerebellum, granule cells are continuously produced and migrate across the molecular layer (ML), which is built by the granule cells themselves, and consists of their axons. We postulate that the granule cell bodies migrate at a fixed velocity with respect to the axonal material through which they move, but that this background material is itself in motion, being continually displaced by the volume of the moving granule cell bodies. These considerations lead to a nonlinear hyperbolic partial differential equation which supports shock-like solutions. Such a discontinuity in granule cell density is observed at the junction of the ML and the inner granule layer (IGL), where the granule cell bodies come to rest.
The research described is joint work with: Shoshana R. Leffler and Daniel H. Turnbull of the Kimmel Center for Biology and Medicine at the Skirball Institute of Biomolecular Medicine, NYU School of Medicine; Alexandra L. Joyner of the Memorial Sloan-Kettering Cancer Center; and Adam Stinchcombe and Jerome K. Percus of the Courant Institute of Mathematical Sciences, New York University.

Jeremy Quastel, University of Toronto
"Exact formulas for KPZ and directed polymers in 1+1 dimensions"

Charles Radin, University of Texas
"Rigidity in solids"
Abstract: Although there appears to be a clear distinction between fluids and solids in their response to shear stress, it is not straightforward to use this to distinguish the phases theoretically; phases are only well defined in the infinite volume limit, but response to shear disappears in that limit. I will discuss a method to overcome this, which has been successfully tested through simulation of the hard disk model. This is joint work with David Aristoff, and was published in J. Stat. Phys. 144 (2011) 1247-1255.

Sidney Redner, Boston University
"Fate of the Kinetic Ising Model in Three Dimensions"
Abstract: What is the fate of a homogeneous, finite-size three-dimensional Ising model that starts at infinite temperature and is suddenly quenched to zero temperature. When the system evolves by Glauber dynamics we find: (i) Domains at long time are strongly interpenetrating and topologically complex, with their average genus growing algebraically with system size; (ii) The long-time state almost always contains "blinker" spins that can flip ad infinitum with no energy cost. (iii) The relaxation is characterized bym ultiple time scales, the longest of which grows exponentially with system size.

Rajarshi Roy, "University of Maryland
Title: Synchronization in Real Optical Networks"
Abstract: We explore synchronization in networks of coupled optoelectronic oscillators in our laboratory. Numerical models are developed and simulations are compared with experimental observations to understand how real networks synchronize and desynchronize as coupling coefficients are varied. Convergence to synchrony is found to depend on the network topology. We find that networks with the same number of nodes and links, and identical eigenvalues of the coupling matrix can exhibit fundamentally different approaches to synchrony, with rather different statistical features.

Harold Scheraga, Cornell University
"The Protein Folding Problem: Structure, Dynamics, Thermodynamics, and Folding Pathways"

Michael Schick, University of Washington
"Rafts in the Plasma Membrane: A Curvature-Induced Microemulsion"
Abstract: To explain the appearance of heterogeneities in the plasma membrane, Ipropose a hypothesis which begins with the observation that fluctuations in the membrane curvature are coupled to the difference between compositions in one leaf and the other. Because of this coupling, the most easily excited fluctuations can occur at non-zero wavenumbers. When the coupling is sufficiently strong, it is well-known that it leads to microphase separation and modulated phases. I note that when the coupling is less strong, the tendency towards modulation remains manifest in a liquid phase that exhibits transient structure of a characteristic size; that is, it is a microemulsion. The characteristic size of the fluctuating domains is estimated to be on the order of 100 nm.

Eric Siggia, Rockefeller University
"Geometry, Epistasis and Developmental Patterning"
Abstract: Developmental signaling networks are composed of dozens of components whose interactions are very difficult to quantify in an embryo. Geometric reasoning enumerates a discrete hierarchy of phenotypic models with a few composite variables whose parameters may be defined by in vivo data. Vulval development in the nematode {it C.~elegans} is a classic model for the integration of two signaling pathways; induction by EGF/Ras and lateral inhibition through Notch/Delta. Existing data for the relative probabilities of the three possible terminal cell types in diverse genetic backgrounds as well as timed ablation of the inductive signal favor one geometric model and suffice to fit most of its parameters. The model is fully dynamic and encompasses both signaling and committment. It then predicts the correlated cell fate probabilities for a cross between any two backgrounds/conditions. The two signaling pathways are combined additively, without interactions, and epistasis only arises from the projection onto discrete cell fates by the dynamics. In this way, the model quantitatively fits genetic experiments purporting to show mutual pathway repression. The model quantifies the contributions of extrinsic vs. intrinsic sources of noise in the penetrance of mutant phenotypes in signaling hypomorphs and explains available experiments with no additional parameters. Data for anchor cell ablation fixes the parameters needed to explain the induction of isolated vulva precursor cells.

Craig A. Tracy, University of California, Davis
"Recent progress and open problems for the asymmetric simple exclusion process"
Abstract: We review recent exact work for the one-dimensional asymmetric simple exclusion process. Some open problems are presented. This is joint work with Harold Widom.

Salvatore Torquato, Princeton University
"Geometry and Physics in High-Dimensional Euclidean Spaces"
Abstract: It is known that the sphere-packing problem and the number-variance problem (closely related to an optimization problem in number theory) can be posed as energy minimizations associated point particles in d-dimensional Euclidean space interacting via certain repulsive pair potentials. Recently, I have reformulated the covering and quantizer problems, well-known in discrete geometry, as the determination of the ground states of interacting particles in d-dimensional Euclidean space that generally involve single-body, two-body, three-body, and higher-body interactions [1]. These reformulations again exemplify the deep interplay between geometry and physics. The covering and quantizer problems have relevance in numerous applications, including wireless communication network layouts, the search of high-dimensional data parameter spaces, stereotactic radiation therapy, data compression, digital communications, meshing of space for numerical analysis, and coding and cryptography, among other examples. The connections between the covering and quantizer problems and the sphere-packing and number-variance problems (related to problems in number theory) are discussed. I also show that disordered saturated sphere packings provide relatively thin (economical) coverings and may yield thinner coverings than the best known lattice coverings in sufficiently large dimensions. I derive improved upper bounds on the quantizer error using sphere-packing solutions, which are generally substantially sharper than an existing upper bound in low to moderately large dimensions. I demonstrate that disordered saturated sphere packings yield relatively good quantizers in sufficiently high dimensions. Finally, I remark on possible applications of the results to the detection of gravitational waves.
[1] S. Torquato, Phys. Rev. E, 82, 056109 (2010).

Benjamin Widom, Cornell University
"Tales of an Obsession: Solvophobia and Solvophilia"
Abstract: This is a story about some work over several years, and with some references to even much older things, on the general theme of how very low solubility of a solute in a solvent manifests itself in the solute-solvent and solute-solute correlation functions (potentials of mean force). With water as solvent these effects are hydrophobia, contrasted with its opposite, hydrophilia; more generally, solvophobia and solvophilia. The story does does not yet have an ending but one may hope for a happy one some day.

Elisabeth Widom, Miami University
"Timescales of Magmatic Processes"
Abstract: Determining the timescales and processes of magma evolution, and the relationship to eruptive behavior and eruptive volume, is critical for understanding the past, present and future behavior of active volcanic systems. In this talk, I will present recent results on the rates of magma evolution and pre-eruptive magma residence timescales based on uranium-series disequilibria analyses of volcanic glass. Our results suggest that longer magma residence timescales result in larger eruptions, and that in some cases magmas can evolve to yield explosive eruptions over timescales as short as 101-102 years.

Michael Widom, Carnegie Mellon University
"Thermodynamics from first principles"
Abstract: Quantum mechanics-based first principles total energy calculations can predict alloy phase diagrams in the limit of low temperature (T=0K). Collecting total energies of many configurations allows explicit calculation of finite temperature partition functions, and hence free energies. The resulting phase diagrams can reveal detailed information not readily available from experiment. As an example, we suggest that the non-stoichiometric compound known as "boron carbide" possesses two distinct low temperature phases: the familiar rhombohedral phase with a broad composition range, as well as a monoclinic phase with the precise stoichiometry B4C. The monoclinic phase loses stability to the rhombohedral phase through an orientational order-disorder transition.

PRESENTATIONS OF TALKS GIVEN AT THE 106th STATISTICAL MECHANICS CONFERENCE