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Questions tagged [free-energy]

Questions about free energy.

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11 votes
1 answer

How to get order constitution data for single equilibrium calculation in Thermo-Calc's TC Python module?

I know that it is possible to get order constitution data for phases when using Thermo-Calc's GUI (e.g. to get "BCC_B2 DISORD" instead of just "BCC_B2") for a single equilibrium ...
sgp45's user avatar
  • 632
7 votes
1 answer

What information about a crystalline solid material goes into calculating phase diagrams in Thermo-Calc, and how?

Gibbs free energy, $G$, for a crystalline solid material could be described as: \begin{equation} G\: =\: H_{T=0}\: +\: H_{T>0}\: +\: \text{ZPE}\: -\: T\cdot S, \end{equation} Where $H$ is enthalpy, ...
Hitanshu Sachania's user avatar
19 votes
1 answer

Difference between potential energy, free energy and Coulomb energy in solid state physics

I often encounter terms such as (Helmholtz, Gibbs) free energy, potential energy and total energy when describing the energy of a physical system at atomic level. Sometimes I stumble upon Coulomb ...
Achintha Ihalage's user avatar
13 votes
1 answer

Are there any MD packages that do proper free energy sampling in the NPT ensemble?

Statistical Mechanics is the basis of molecular level calculations of properties and averages. Nowadays free energy calculations are fairly "turn-the-crank", which is not necessarily a good ...
B. Kelly's user avatar
  • 4,376
10 votes
1 answer

Can I compute the free energy difference in (temporally) nearby micro-states using the Zwanzig equation for Free Energy Perturbation?

I wanted to understand the Free Energy Perturbation in an NVT ensemble. Wikipedia explains it as: $$ \tag{1} \Delta F = F_1 - F_0 = -\kappa T \ln \left<\exp\left( \frac{-(E_1-E_0)}{\kappa T}\right)...
fireball.1's user avatar
  • 1,083
9 votes
1 answer

How can we calculate the Gibbs free energy from first principles?

I am trying to calculate the Gibbs free energy for a bulk material. Since DFT ground state calculations give the energy at 0K, a temperature dependent part has to be added in this to obtain correct ...
Shahid Sattar's user avatar
6 votes
1 answer

Persistent errors in single equilibrium calculations (Thermo-Calc)

When running single point equilibrium calculations on an array of compositions I come across some compositions (for specific examples see below) that return the error ...
sgp45's user avatar
  • 632
5 votes
1 answer

How to calculate phase regions using CALPHAD for higher order systems (>3 elements)?

I primarily use Thermo-Calc so I will use that to describe my problem but I am interested to hear general CALPHAD insight as well. Using Thermo-Calc I can quickly get an idea of the phase regions ...
sgp45's user avatar
  • 632
3 votes
0 answers

What input setting in Quantum ESPRESSO will allow me to calculate the free energy of a solid? [closed]

I understand that it's possible to calculate the Gibbs free energy of a system ab initio, see for example: How can we calculate the Gibbs free energy from first principles? I'm wondering how I can do ...
Paulie Bao's user avatar
  • 3,973