Questions tagged [gibbs-free-energy]

Refers to the thermodynamic quantity representing both enthalpy and entropy factors.

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1answer
34 views

Thermo-Calc: how to suspend specific composition sets?

I am attempting to calculate the driving force of nucleation for several different precipitate phases using TC-Python. To this I want to suspend all phases, except for the matrix phase (e.g. FCC_L12). ...
6
votes
1answer
52 views

Is it possible to analytically solve for a particular phase region of a CALPHAD database? (instead of guessing and checking)

As I understand it, a given CALPHAD database is essentially just a set of equations that model the Gibbs free energy of each phase within a given alloy system (set of elements). Typically, the main ...
11
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0answers
70 views

Calculation of Gibbs free energy of Mg+ ion using VASP [closed]

I am trying to replicate the $\Delta G_0$ part from this paper. According to the paper, $\Delta G_0$ is 30% of the difference between atomic energy for per $\ce{Mg}$ atom in the bulk structure and the ...
6
votes
1answer
89 views

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, ...
11
votes
1answer
121 views

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 ...
6
votes
0answers
72 views

Why does Thermo-Calc one axis equilibrium calculation get stuck in never ending loop? [closed]

I've been trying to run a Thermo-Calc one axis equilibrium calculation on some quaternary alloys in the TCHEA4 database. Most of the calculations work fine, but for some alloys it gets stuck in a loop ...
8
votes
1answer
97 views

For a Thermo-Calc database, is it possible to view the equation/parameters of the Gibbs free energy models?

I want to get the equations that model free energy for a given phase in a given alloy system (see attached image). I do not just want to get values of free energy for specific compositions. Is it ...
11
votes
1answer
183 views

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 ...
10
votes
1answer
132 views

MM-GBSA from Induced Fit Docking on Maestro

How can an MM-GBSA(molecular mechanics energies combined with generalized Born and surface area continuum solvation) calculation be done from an induced fit docking (IFD) output? I performed an IFD ...
9
votes
1answer
66 views

VASP output energy

Which VASP output energy, after sigma -> 0 or before, do you use when combining with zero point energy and vibrational entropy obtained via vtst tools? (Vtst tools provide the vibrational frequencies ...
12
votes
1answer
139 views

What are the methods for calculating solvation effects in free energies and how do they compare?

I've just found this paper (J. Chem. Phys. 141, 174106 (2014)) that deals with the translational and rotational entropies in solution. The method is promising but, unfortunately, requires a ...
19
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1answer
250 views

What do phonon dispersion (or lattice dynamics) studies include?

I use the codes phonopy and phonopy-qha for phonon dispersion studies. phonopy-qha gives ...
14
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3answers
108 views

What thermodynamic data is collected in order to build a CALPHAD model?

To build a model using the CALPHAD approach, i.e. Gibbs free energy as a function of composition and temperature, typically taking the form of a Redlich-Kister polynomial, what kind of thermodynamic ...