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Gibbs Free Energy

Gibbs Free Energy

One of the challenges of using the second law of thermodynamics to determine if a process is spontaneous is that it requires measurements of the entropy change for the system and the entropy change for the surroundings. An alternative approach involving a new thermodynamic property defined in terms of system properties only was introduced in the late nineteenth century by American mathematician Josiah Willard Gibbs. This new property is called the Gibbs free energy (G) (or simply the free...

An Introduction to Free Energy

An Introduction to Free Energy

How can we compare the energy that releases from one reaction to that of another reaction? We use a measurement of free energy to quantitate these energy transfers. Scientists call this free energy Gibbs free energy (abbreviated with the letter G) after Josiah Willard Gibbs, the scientist who developed the measurement. According to the second law of thermodynamics, all energy transfers involve losing some energy in an unusable form such as heat, resulting in entropy. Gibbs free energy...

Calculating Standard Free Energy Changes

Calculating Standard Free Energy Changes

The free energy change for a reaction that occurs under the standard conditions of 1 bar pressure and at 298 K is called the standard free energy change. Since free energy is a state function, its value depends only on the conditions of the initial and final states of the system. A convenient and common approach to the calculation of free energy changes for physical and chemical reactions is by use of widely available compilations of standard state thermodynamic data. One method involves the...

Free Energy

Free Energy

Free energy—abbreviated as G for the scientist Gibbs who discovered it—is a measurement of useful energy that can be extracted from a reaction to do work. It is the energy in a chemical reaction that is available after entropy is accounted for. Reactions that take in energy are considered endergonic and reactions that release energy are exergonic. Plants carry out endergonic reactions by taking in sunlight and carbon dioxide to produce glucose and oxygen. Animals, in turn, break...

Gibbs Free Energy and Thermodynamic Favorability

Gibbs Free Energy and Thermodynamic Favorability

The spontaneity of a process depends upon the temperature of the system. Phase transitions, for example, will proceed spontaneously in one direction or the other depending upon the temperature of the substance in question. Likewise, some chemical reactions can also exhibit temperature-dependent spontaneities. To illustrate this concept, the equation relating free energy change to the enthalpy and entropy changes for the process is considered:

Free Energy Changes for Nonstandard States

Free Energy Changes for Nonstandard States

The free energy change for a process taking place with reactants and products present under nonstandard conditions (pressures other than 1 bar; concentrations other than 1 M) is related to the standard free energy change according to this equation:

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Deep Neural Networks for Image-Based Dietary Assessment

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Published on: March 13, 2021

Computing Absolute Free Energy with Deep Generative Models.

Xinqiang Ding¹, Bin Zhang¹

¹Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.

The Journal of Physical Chemistry. B

|November 4, 2020

Summary

This summary is machine-generated.

This study introduces a novel framework for calculating absolute free energy, crucial for drug design and materials science. The method uses deep generative models and a reference state to enable accurate free energy difference computations.

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Area of Science:

Computational Chemistry
Statistical Mechanics
Machine Learning

Background:

Accurate free energy calculations are vital for drug design and materials engineering.
Computing absolute free energy allows direct assessment of relative state stability.
Existing methods often require intermediate states or approximations.

Purpose of the Study:

To present a general framework for calculating the absolute free energy of a target state.
To enable free energy calculations without relying on intermediate states.
To provide a valuable strategy for computing free energy differences.

Main Methods:

Defining a reference state using tractable deep generative models with locally sampled configurations.
Setting the absolute free energy of the reference state to zero by design.
Calculating the free energy of the state of interest as the difference from the reference state.

Main Results:

The framework was successfully applied to both discrete and continuous systems.
The Bennett acceptance ratio method demonstrated superior accuracy and efficiency compared to work-based approximations.
The proposed method effectively computes absolute free energy differences.

Conclusions:

The developed framework offers a robust approach for absolute free energy calculations.
This method enhances the accuracy and efficiency of free energy estimations.
The approach is anticipated to be a valuable tool in computational chemistry and related fields.