First-principles model study of the phase stabilities of dilute Fe-Cu alloys: Role of vibrational free energy

2009 ◽  
Vol 80 (5) ◽  
Author(s):  
D. Reith ◽  
R. Podloucky
Keyword(s):  
Free Energy ◽  
First Principles ◽  
Cu Alloys ◽  
Model Study ◽  
Vibrational Free Energy

scholarly journals First Principles Calculations of Vibrational Free Energy Estimated by the Quasi-Harmonic Approximation

2009 ◽  
Vol 73 (8) ◽  
pp. 566-570 ◽  
Author(s):  
Shigeto R. Nishitani ◽  
Ryohei Takeda ◽  
Hideki Ishii ◽  
Yosuke Yamamoto ◽  
Tadaaki Kaneko
Keyword(s):  
Free Energy ◽  
First Principles ◽  
Harmonic Approximation ◽  
First Principles Calculations ◽  
Vibrational Free Energy

scholarly journals Theoretical insights into C–H bond activation of methane by transition metal clusters: the role of anharmonic effects

2021 ◽  
Author(s):  
Preeti Bhumla ◽  
Manish Kumar ◽  
Saswata Bhattacharya
Keyword(s):  
Free Energy ◽  
Md Simulation ◽  
Bond Activation ◽  
Integration Method ◽  
Excess Free Energy ◽  
Configurational Entropy ◽  
Transition Metal Clusters ◽  
Vibrational Free Energy ◽  
Free Energy Contribution

To incorporate the anharmonicity in the vibrational free energy contribution to the configurational entropy, we evaluate the excess free energy of clusters numerically by a thermodynamic integration method with ab initio molecular dynamics (aiMD) simulation inputs.

Chemical equilibrium and chemical kinetics

2018 ◽  
Author(s):  
Dennis Sherwood ◽  
Paul Dalby
Keyword(s):  
Free Energy ◽  
Equilibrium Constant ◽  
Gibbs Free Energy ◽  
Chemical Kinetics ◽  
Chemical Equilibrium ◽  
First Principles ◽  
Effect Of Temperature ◽  
Total System ◽  
Free Energies

Building on the previous chapter, this chapter examines gas phase chemical equilibrium, and the equilibrium constant. This chapter takes a rigorous, yet very clear, ‘first principles’ approach, expressing the total Gibbs free energy of a reaction mixture at any time as the sum of the instantaneous Gibbs free energies of each component, as expressed in terms of the extent-of-reaction. The equilibrium reaction mixture is then defined as the point at which the total system Gibbs free energy is a minimum, from which concepts such as the equilibrium constant emerge. The chapter also explores the temperature dependence of equilibrium, this being one example of Le Chatelier’s principle. Finally, the chapter links thermodynamics to chemical kinetics by showing how the equilibrium constant is the ratio of the forward and backward rate constants. We also introduce the Arrhenius equation, closing with a discussion of the overall effect of temperature on chemical equilibrium.

scholarly journals Free Energy of Metals from Quasi-Harmonic Models of Thermal Disorder

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 195
Author(s):  
Pavel A. Korzhavyi ◽  
Jing Zhang
Keyword(s):  
Free Energy ◽  
First Principles ◽  
Density Functional ◽  
Helmholtz Free Energy ◽  
Complex Materials ◽  
Predictive Capability ◽  
Temperature Dependent ◽  
Disordered Alloys ◽  
Thermal Disorder ◽  
Structure Calculations

A simple modeling method to extend first-principles electronic structure calculations to finite temperatures is presented. The method is applicable to crystalline solids exhibiting complex thermal disorder and employs quasi-harmonic models to represent the vibrational and magnetic free energy contributions. The main outcome is the Helmholtz free energy, calculated as a function of volume and temperature, from which the other related thermophysical properties (such as temperature-dependent lattice and elastic constants) can be derived. Our test calculations for Fe, Ni, Ti, and W metals in the paramagnetic state at temperatures of up to 1600 K show that the predictive capability of the quasi-harmonic modeling approach is mainly limited by the electron density functional approximation used and, in the second place, by the neglect of higher-order anharmonic effects. The developed methodology is equally applicable to disordered alloys and ordered compounds and can therefore be useful in modeling realistically complex materials.

Role of dislocations in the bcc-hcp transition under high pressure: A first-principles approach in beryllium

2020 ◽  
Vol 4 (6) ◽  
Author(s):  
Vanessa Riffet ◽  
Bernard Amadon ◽  
Nicolas Bruzy ◽  
Christophe Denoual
Keyword(s):  
High Pressure ◽  
First Principles
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