# Questions tagged [free-energy]

Questions about free energy.

14 questions
Filter by
Sorted by
Tagged with
1 vote
23 views

### Relationship between grand potential and free energy?

What is the fundamental relationship between grand potential and free energy? In other words, what assumptions need to be made in order to obtain the free energy equation rather than the grand ...
• 101
93 views

### Water Dimer and Free Energy Perturbation (FEP)

I am trying to understand the FEP in the context of water dimer. Let's say I want to calculate $\Delta A$, the free energy change for the following reaction: $\ce{H_2O +H_2O\rightarrow H_2O-H_2O}$, ...
• 235
90 views

### Calculating enthalpy of a chemical reaction using DFT

Let's say we have a decomposition reaction $A \rightarrow B + C$ how would I go about calcualting the Enthalpy of this chemical reaction using VASP. I am gonna describe what I am thinking below please ...
• 1,581
170 views

### How to calculate the Gibbs free energy for a reaction?

I am trying to learn how to calculate Gibbs free energy for a reaction. Assuming a reaction for two-dimensional TMDCs: MoS2 (solid) + 2Se(gas) ---> MoSe2 (solid)+ 2S (gas) I can calculate the ...
• 1,326
139 views

### How to estimate chemical potential at a temperature?

Fermi level is electron chemical potential at 0K and we can obtain it from DFT calculation. However, the chemical potential is dependent on temperature. But I only find the equation for gas or simple ...
• 1,813
148 views

### Gibbs free energy modification after finishing NEB?

I have finished the NEB calculation, but it seems all the energy I got is Internal energy instead of Gibbs free energy, so do I need to do Gibbs free energy modification? Is there any standard ...
• 1,843
203 views

### 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 ...
• 3,609
136 views

### Should one consider the spatial degeneracies of the electronic state while calculating the Gibbs free energy?

The Gibbs free energy of a molecule is generally expressed as a sum of translational, rotational, vibrational, electronic and nuclear contributions. The electronic contribution $G_{elec}$ is formally ...
• 7,498
112 views

### Software for generating ensembles of dimer pairs of organic molecules

For two organic molecules of essentially unlimited size (up to and including, and sometimes exceeding MW = 1000 g/mol), I would like to generate all possible dimer pairs in vacuum. The pairs may be ...
• 1,030
97 views

### Single electron transfer periodic DFT in VASP [closed]

I have the following question: I am currently studying the electrocatalytic $\ce{CO2}$ reduction reaction (CO2RR) on $\ce{Cu}$ materials using periodic DFT calculations and I am using the ...
197 views

### 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)...
• 1,083
160 views

### Calculate free energy for a canonical (NVT) ensemble [closed]

Note: Users wishing to answer this question may write a comment or a message in the chat indicating their desire for the question to be re-opened. I have an NVT ensemble of water molecules (liquid) ...
• 1,083
819 views

### 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 ...
• 1,952