scholarly journals Contracting cosmologies and the swampland

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Heliudson Bernardo ◽  
Robert Brandenberger
Keyword(s):  
Potential Energy ◽  
Scalar Fields ◽  
Negative Potential ◽  
Local Minima ◽  
Entropy Bound ◽  
Relative Slope

Abstract We consider the cosmology obtained using scalar fields with a negative potential energy, such as employed to obtain an Ekpyrotic phase of contraction. Applying the covariant entropy bound to the tower of states dictated by the distance conjecture, we find that the relative slope of the potential |V′|/|V| is bounded from below by a constant of the order one in Planck units. This is consistent with the requirement to obtain slow Ekpyrotic contraction. We also derive a refined condition on the potential which holds near local minima of a negative potential.

Global and local minima of protonated acetonitrile clusters

2020 ◽  
Vol 44 (40) ◽  
pp. 17558-17569 ◽  
Author(s):  
Alhadji Malloum ◽  
Jeanet Conradie
Keyword(s):  
Hydrogen Bonds ◽  
Potential Energy ◽  
Potential Energy Surfaces ◽  
Local Minima ◽  
Energy Surfaces ◽  
Global And Local

Potential energy surfaces of protonated acetonitrile clusters have been explored to locate global and local minima energy structures. The structures are stabilized by strong hydrogen bonds, anti-parallel dimers, dipole–dipole and CH⋯N interactions.

scholarly journals THE BIANCHI TYPE I MODEL WITH TWO INTERACTING SCALAR FIELDS

2007 ◽  
Vol 16 (11) ◽  
pp. 1845-1852 ◽  
Author(s):  
VLADIMIR FOLOMEEV
Keyword(s):  
Potential Energy ◽  
Early Universe ◽  
Special Form ◽  
Bianchi Type ◽  
Scalar Fields ◽  
Analytic Solutions ◽  
Type I ◽  
Anisotropic Model ◽  
Friedmann Model ◽  
Matter Fields

The flat anisotropic model of the early Universe is considered. Two interacting scalar fields with a special form of potential energy are a source of matter fields. Analytic solutions for stages of inflation and preheating are found. It is shown that the solutions tend asymptotically to an isotropic Friedmann model.

On the Stability of Rigid Multibody Systems With Applications to Robotic Grasping and Locomotion

2015 ◽  
Vol 7 (4) ◽  
Author(s):  
Péter L. Várkonyi
Keyword(s):  
Potential Energy ◽  
Wide Class ◽  
Multibody Systems ◽  
Local Minima ◽  
Small Perturbations ◽  
Rigid Multibody Systems ◽  
The Stability ◽  
External Forces ◽  
Rigid Multibody ◽  
Accelerating Motion

This paper shows that the equilibria of a wide class of multibody systems with quasi-rigid, frictional, or frictionless supports correspond to local minima of their potential energy; hence they are stable against small perturbations of external forces. This is a generalization of a theorem by Howard and Kumar on the stability of a single rigid body held by a gripper. It is also demonstrated that ambiguous equilibria (those, which coexist with the possibility of accelerating motion) may be stable. These results help finding safe grasps on nonrigid objects and assessing the stability of quasi-static robots moving over complex terrains.

scholarly journals Decoding the energy landscape: extracting structure, dynamics and thermodynamics

2012 ◽  
Vol 370 (1969) ◽  
pp. 2877-2899 ◽  
Author(s):  
David J. Wales
Keyword(s):  
Potential Energy ◽  
Energy Surface ◽  
Condensed Matter ◽  
Energy Landscape ◽  
Local Minima ◽  
Atomic And Molecular Clusters ◽  
Computational Framework ◽  
Interparticle Forces ◽  
Structure Dynamics ◽  
Potential Energy Landscape

Describing a potential energy surface in terms of local minima and the transition states that connect them provides a conceptual and computational framework for understanding and predicting observable properties. Visualizing the potential energy landscape using disconnectivity graphs supplies a graphical connection between different structure-seeking systems, which can relax efficiently to a particular morphology. Landscapes involving competing morphologies support multiple potential energy funnels, which may exhibit characteristic heat capacity features and relaxation time scales. These connections between the organization of the potential energy landscape and structure, dynamics and thermodynamics are common to all the examples presented, ranging from atomic and molecular clusters to biomolecules and soft and condensed matter. Further connections between motifs in the energy landscape and the interparticle forces can be developed using symmetry considerations and results from catastrophe theory.

Atomic charges for conformationally rich molecules obtained through a modified principal component regression

2018 ◽  
Vol 20 (4) ◽  
pp. 2890-2903 ◽  
Author(s):  
Tymofii Yu. Nikolaienko ◽  
Leonid A. Bulavin
Keyword(s):  
Dipole Moment ◽  
Potential Energy ◽  
Potential Energy Surface ◽  
Regression Model ◽  
Energy Surface ◽  
Principal Component Regression ◽  
Principal Component ◽  
Atomic Charges ◽  
Local Minima ◽  
Fixed Set

A modification of the principal component regression model is proposed for obtaining a fixed set of atomic charges (referred to as dipole-derived charges) optimized for reproducing the dipole moment of a conformationally rich molecule, i.e., a molecule with multiple local minima on the potential energy surface.

A random walk to local minima and saddle points on a potential energy surface. A strategy based on simulated annealing

1996 ◽  
Vol 250 (2) ◽  
pp. 238-246 ◽  
Author(s):  
P. Chaudhury ◽  
P. Dutta ◽  
P. Bandyopadhyay ◽  
P. Sarkar ◽  
S.P. Bhattacharyya
Keyword(s):  
Simulated Annealing ◽  
Random Walk ◽  
Potential Energy ◽  
Potential Energy Surface ◽  
Energy Surface ◽  
Saddle Points ◽  
Local Minima
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