Nonlocal gradient corrections to the exchange free energy of an inhomogeneous many-fermion system at finite temperature

1993 ◽  
Vol 88 (1) ◽  
pp. 81-85 ◽  
Author(s):  
D.J.W. Geldart ◽  
E. Dunlap ◽  
M.L. Glasser ◽  
Mark R.A. Shegelski
Keyword(s):  
Free Energy ◽  
Finite Temperature ◽  
Fermion System ◽  
Gradient Corrections

Nonlocal exchange contribution to the free energy of inhomogeneous many–fermion systems. I: Formulation of the gradient expansion

1994 ◽  
Vol 72 (1-2) ◽  
pp. 1-6 ◽  
Author(s):  
E. Dunlap ◽  
D. J. W. Geldart
Keyword(s):  
Free Energy ◽  
Finite Temperature ◽  
Interparticle Interaction ◽  
Fermion System ◽  
Exchange Contribution ◽  
Gradient Expansion ◽  
First Order ◽  
Fermion Systems ◽  
Explicit Representations ◽  
Arbitrary Velocity

Nonlocal exchange contributions to the free energy of a weakly inhomogeneous many-fermion system at finite temperature are obtained to first order in the interparticle interaction. Explicit representations are given for the second-order gradient coefficient Bx (n(r); T). These results apply for arbitrary velocity-independent interparticle interaction and arbitrary temperature.

scholarly journals Color singlet and adjoint free energy at finite temperature

2009 ◽  
Author(s):  
Alexei Bazavov ◽  
Peter Petreczky ◽  
Alexander Velytsky
Keyword(s):  
Free Energy ◽  
Finite Temperature ◽  
Color Singlet

scholarly journals CASIMIR ENERGY OF A DILUTE DIELECTRIC BALL AT ZERO AND FINITE TEMPERATURE

2002 ◽  
Vol 17 (06n07) ◽  
pp. 790-793 ◽  
Author(s):  
V. V. NESTERENKO ◽  
G. LAMBIASE ◽  
G. SCARPETTA
Keyword(s):  
Free Energy ◽  
Electromagnetic Field ◽  
Angular Momentum ◽  
High Temperature ◽  
Finite Temperature ◽  
Bessel Functions ◽  
Thermodynamic Characteristics ◽  
Casimir Energy ◽  
Addition Theorem ◽  
Temperature Expansion

The basic results in calculations of the thermodynamic functions of electromagnetic field in the background of a dilute dielectric ball at zero and finite temperature are presented. Summation over the angular momentum values is accomplished in a closed form by making use of the addition theorem for the relevant Bessel functions. The behavior of the thermodynamic characteristics in the low and high temperature limits is investigated. The T3-term in the low temperature expansion of the free energy is recovered (this term has been lost in our previous calculations).

Free-Energy Calculations

2006 ◽  
Author(s):  
Vasily Bulatov ◽  
Wei Cai
Keyword(s):  
Free Energy ◽  
Melting Temperature ◽  
Open System ◽  
Finite Temperature ◽  
Liquid State ◽  
Crystalline State ◽  
Minimum Energy ◽  
Temperature Limit ◽  
Free Energy Calculations ◽  
Energy Calculations

Free energy is of central importance for understanding the properties of physical systems at finite temperatures. While in the zero temperature limit the system should evolve to a state of minimum energy (Section 2.3), this is not necessarily the case at a finite temperature. When an open system exchanges energy with the outside world (a thermostat) and maintains a constant temperature, its evolution proceeds towards minimizing its free energy. For example, a crystal turns into a liquid when the temperature exceeds its melting temperature precisely because the free energy of the liquid state becomes lower than that of the crystalline state. In the context of dislocation simulations, free energy is all important when one has to decide which of the possible core configurations the dislocation is likely to adopt at a given temperature.

Finite-temperature effects in enzymatic reactions — Insights from QM/MM free-energy simulations

2009 ◽  
Vol 87 (10) ◽  
pp. 1322-1337 ◽  
Author(s):  
Hans Martin Senn ◽  
Johannes Kästner ◽  
Jürgen Breidung ◽  
Walter Thiel
Keyword(s):  
Free Energy ◽  
Finite Temperature ◽  
Temperature Effects ◽  
Density Functional ◽  
Umbrella Sampling ◽  
Chorismate Mutase ◽  
Enzymatic Reactions ◽  
Energy Data ◽  
Energy Simulations ◽  
Entropic Contribution

We report potential-energy and free-energy data for three enzymatic reactions: carbon–halogen bond formation in fluorinase, hydrogen abstraction from camphor in cytochrome P450cam, and chorismate-to-prephenate Claisen rearrangement in chorismate mutase. The results were obtained by combined quantum mechanics/molecular mechanics (QM/MM) optimizations and two types of QM/MM free-energy simulations (free-energy perturbation and umbrella sampling) using semi-empirical or density-functional QM methods. Based on these results and our previously published free-energy data on electrophilic substitution in para-hydroxybenzoate hydroxylase, we discuss the importance of finite-temperature effects in the chemical step of enzyme reactions. We find that the entropic contribution to the activation barrier is generally rather small, usually of the order of 5 kJ mol–1 or less, consistent with the notion that enzymes bind and pre-organize the reactants in the active site. A somewhat larger entropic contribution is encountered in the case of chorismate mutase where the pericyclic transition state is intrinsically more rigid than the chorismate reactant (also in the enzyme). The present results suggest that barriers from QM/MM geometry optimization may often be close to free-energy barriers for the chemical step in enzymatic reactions.

scholarly journals EFFECTS OF STRAIN COUPLING AND MARGINAL DIMENSIONALITY IN THE NATURE OF PHASE TRANSITION IN QUANTUM PARAELECTRICS

2013 ◽  
Vol 27 (08) ◽  
pp. 1350028 ◽  
Author(s):  
NABYENDU DAS
Keyword(s):  
Free Energy ◽  
Critical Point ◽  
Finite Temperature ◽  
Order Parameter ◽  
Quantum Critical Point ◽  
Order Transition ◽  
Zero Temperature ◽  
First Order ◽  
Quantum Paraelectrics ◽  
First Order Transition

Here a recently observed weak first order transition in doped SrTiO 3 [Taniguchi, Itoh and Yagi, Phys. Rev. Lett.99, 017602 (2007)] is argued to be a consequence of the coupling between strain and order parameter fluctuations. Starting with a semi-microscopic action, and using renormalization group equations for vertices, we write the free energy of such a system. This fluctuation renormalized free energy is then used to discuss the possibility of first order transition at zero temperature as well as at finite temperature. An asymptotic analysis predicts small but a finite discontinuity in the order parameter near a mean field quantum critical point at zero temperature. In case of finite temperature transition, near quantum critical point such a possibility is found to be extremely weak. Results are in accord with some experimental findings on quantum paraelectrics such as SrTiO 3 and KTaO 3.

scholarly journals Free energy versus internal energy potential for heavy quark systems at finite temperature

2014 ◽  
Vol 931 ◽  
pp. 607-611
Author(s):  
Taesoo Song ◽  
Su Houng Lee ◽  
Kenji Morita ◽  
Che Ming Ko
Keyword(s):  
Free Energy ◽  
Heavy Quark ◽  
Internal Energy ◽  
Finite Temperature ◽  
Energy Potential

scholarly journals MAGNETIC INSTABILITY IN A PARITY INVARIANT TWO-DIMENSIONAL FERMION SYSTEM

2000 ◽  
Vol 14 (14) ◽  
pp. 1441-1449 ◽  
Author(s):  
M. ELIASHVILI ◽  
G. TSITSISHVILI
Keyword(s):  
High Temperature ◽  
Temperature Regime ◽  
Ground State ◽  
Finite Temperature ◽  
Two Dimensional ◽  
Fermion System ◽  
Temperature Analysis ◽  
Magnetic Instability ◽  
High Temperature Regime

We consider the parity invariant QED2+1 where the matter is represented as a mixture of fermions with opposite spins. It is argued that the perturbative ground state of the system is unstable with respect to the formation of magnetized ground state. Carrying out the finite temperature analysis we show that the magnetic instability disappears in the high temperature regime.

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