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Publications

Information geometry for multiparameter models: new perspectives on the origin of simplicity

Cornell Affiliated Author(s)
Author
K.N. Quinn
M.C. Abbott
M.K. Transtrum
B.B. Machta
J.P. Sethna
Abstract

Complex models in physics, biology, economics, and engineering are oftensloppy, meaning that the model parameters are not well determined by the model predictions for collective behavior. Many parameter combinations can vary over decades without significant changes in the predictions. This review uses information geometry to explore sloppiness and its deep relation to emergent theories. We introduce themodel manifoldof predictions, whose coordinates are the model parameters. Itshyperribbonstructure explains why only a few parameter combinations matter for the behavior.

Journal
Reports on progress in physics. Physical Society (Great Britain)
Date Published
Group (Lab)
James Sethna Group

Universal scaling for disordered viscoelastic matter near the onset of rigidity

Author
Danilo Liarte
Stephen Thornton
Eric Schwen
Itai Cohen
Debanjan Chowdhury
James Sethna
Abstract

The onset of rigidity in interacting liquids, as they undergo a transition to a disordered solid, is associated with a rearrangement of the low-frequency vibrational spectrum. In this Letter, we derive scaling forms for the singular dynamical response of disordered viscoelastic networks near both jamming and rigidity percolation. Using effective-medium theory, we extract critical exponents, invariant scaling combinations, and analytical formulas for universal scaling functions near these transitions.

Journal
Physical Review E
Date Published
Group (Lab)
Debanjan Chowdhury Group
Itai Cohen Group
James Sethna Group

Dissipation by surface states in superconducting radio-frequency cavities

Author
S. Deyo
M. Kelley
N. Sitaraman
T. Oseroff
D.B. Liarte
Tomas Arias
M. Liepe
J.P. Sethna
Abstract

Recent experiments on superconducting cavities have found that under large rf electromagnetic fields the quality factor can improve with increasing field amplitude, a so-called "anti-Q slope."Linear theories of dissipation break down under these extreme conditions and are unable to explain this behavior. We numerically solve the Bogoliubov-de Gennes equations at the surface of a superconductor in a parallel AC magnetic field, finding that at large fields there are quasiparticle surface states with energies below the bulk value of the superconducting gap.

Journal
Physical Review B
Date Published
Group (Lab)
James Sethna Group
Tomas Arias Group

Reaction rates and the noisy saddle-node bifurcation: Renormalization group for barrier crossing

Cornell Affiliated Author(s)
Author
D. Hathcock
J.P. Sethna
Abstract

Barrier crossing calculations in chemical reaction-rate theory typically assume that the barrier is large compared to the temperature. When the barrier vanishes, however, there is a qualitative change in behavior. Instead of crossing a barrier, particles slide down a sloping potential. We formulate a renormalization group description of this noisy saddle-node transition. We derive the universal scaling behavior and corrections to scaling for the mean escape time in overdamped systems with arbitrary barrier height.

Journal
Physical Review Research
Date Published
Research Area
Group (Lab)
James Sethna Group

Analysis of magnetic vortex dissipation in Sn-segregated boundaries in Nb3Sn superconducting RF cavities

Author
J. Carlson
A. Pack
M.K. Transtrum
J. Lee
D.N. Seidman
D.B. Liarte
N.S. Sitaraman
A. Senanian
M.M. Kelley
J.P. Sethna
Tomas Arias
S. Posen
Abstract

We study mechanisms of vortex nucleation in Nb3Sn superconducting RF (SRF) cavities using a combination of experimental, theoretical, and computational methods. Scanning transmission electron microscopy imaging and energy dispersive spectroscopy of some Nb3Sn cavities show Sn segregation at grain boundaries in Nb3Sn with Sn concentration as high as ∼35 at. % and widths ∼3 nm in chemical composition. Using ab initio calculations, we estimate the effect excess tin has on the local superconducting properties of the material.

Journal
Physical Review B
Date Published
Group (Lab)
James Sethna Group
Tomas Arias Group

The OpenKIM processing pipeline: A cloud-based automatic material property computation engine

Cornell Affiliated Author(s)
Author
D.S. Karls
M. Bierbaum
A.A. Alemi
R.S. Elliott
J.P. Sethna
E.B. Tadmor
Abstract

The Open Knowledgebase of Interatomic Models (OpenKIM) is a framework intended to facilitate access to standardized implementations of interatomic models for molecular simulations along with computational protocols to evaluate them. These protocols include tests to compute material properties predicted by models and verification checks to assess their coding integrity.

Journal
Journal of Chemical Physics
Date Published
Research Area
Group (Lab)
James Sethna Group

Visualizing probabilistic models in Minkowski space with intensive symmetrized Kullback-Leibler embedding

Cornell Affiliated Author(s)
Author
H.K. Teoh
K.N. Quinn
J. Kent-Dobias
C.B. Clement
Q. Xu
J.P. Sethna
Abstract

We show that the predicted probability distributions for any N-parameter statistical model taking the form of an exponential family can be explicitly and analytically embedded isometrically in a N+N-dimensional Minkowski space. That is, the model predictions can be visualized as control parameters are varied, preserving the natural distance between probability distributions. All pairwise distances between model instances are given by the symmetrized Kullback-Leibler divergence.

Journal
Physical Review Research
Date Published
Group (Lab)
James Sethna Group

Unusual scaling for two-dimensional avalanches: Curing the faceting and scaling in the lower critical dimension

Cornell Affiliated Author(s)
Author
L.X. Hayden
A. Raju
J.P. Sethna
Abstract

The nonequilibrium random-field Ising model is well studied, yet there are outstanding questions. In two dimensions, power-law scaling approaches fail and the critical disorder is difficult to pin down. Additionally, the presence of faceting on the square lattice creates avalanches that are lattice dependent at small scales. We propose two methods which we find solve these issues. First, we perform large-scale simulations on a Voronoi lattice to mitigate the effects of faceting.

Journal
Physical Review Research
Date Published
Group (Lab)
James Sethna Group

Yield Precursor Dislocation Avalanches in Small Crystals: The Irreversibility Transition

Cornell Affiliated Author(s)
Author
X. Ni
H. Zhang
D.B. Liarte
L.W. McFaul
K.A. Dahmen
J.P. Sethna
J.R. Greer
Abstract

The transition from elastic to plastic deformation in crystalline metals shares history dependence and scale-invariant avalanche signature with other nonequilibrium systems under external loading such as colloidal suspensions.

Journal
Physical Review Letters
Date Published
Group (Lab)
James Sethna Group