# Tag Info

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### What is the appropriate way of determining a value for the Hubbard-like potential U for LDA+U / GGA+U calculations?

This is a bit late, but I would say the short answer to your direct question is: technically no, there is no "standard" reliable way, since there are several approaches to determining U self-...

### In molecular mechanics, how are van der Waals forces modelled?

Additional to Alone Programmer's answer. The Lennard-Jones Potential (LJ 12-6) is the standard, but is not unique, in some cases the factor of 6 is changed to 8 to simulate better the hydrogen bonds. ...

### In molecular mechanics, how are van der Waals forces modelled?

You are looking for Lennard-Jones potential. Basically, the interatomic interaction is modeled by this formula: U(r) = 4 \epsilon \Bigg [ \Big ( \frac{\sigma}{r} \Big )^{12} - \Big ( \frac{\sigma}{...
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### In molecular mechanics, how are van der Waals forces modelled?

First I will try to directly answer this question: In terms of energy, how are van der Waals forces modelled (are there formulas that govern these)? The most common way to model the potential ...

### What is the appropriate way of determining a value for the Hubbard-like potential U for LDA+U / GGA+U calculations?

You can calculate U in an ab initio way via linear response theory, for instance. See an example here. However, there is no guarantee that a linear response U value is empirically ideal. That is part ...

### What is the appropriate way of determining a value for the Hubbard-like potential U for LDA+U / GGA+U calculations?

The answer is based on Chapter 1 - The DFT+U: Approaches, Accuracy, and Applications from the book Density Functional Calculations: Recent Progresses of Theory and Application For practical ...

### How do you incorporate hydrogen bonding into molecular simulations?

The short answer is that, while hydrogen bonds do have some covalent character, you can mimic that covalent character by increasing the electrostatic term. For example you can specify point charges to ...
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### How does one compute the boiling point of a liquid made of a particular molecule?

I would like to start off by saying this is first and foremost a thermodynamic problem. Secondly, and as a result of thermodynamics, refer to Gibbs Phase Rule which says \begin{equation} F = C - P + 2 ...
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### Is it okay to use semi-empirical methods to optimize structures if I perform high-level energy calculations?

I generally try to use the most accurate methods that my resources will allow me to use, within a reasonable budget for the desired accuracy. If you're interested in 20 water molecules or 60 atoms (...

### Simulating breaking bonds in molecular dynamics

You can do something with Lennard-Jones potentials instead of harmonic ones. I know this has been done for Coarse-Grained MD simulations using Go-Martini models as in https://pubs.acs.org/doi/abs/10....