# Tag Info

### Generating special quasirandom structures (SQS) for surface calculations?

First of all, it's better to define the terms here because probably not all the people here are familiar with SQS right away. SQS is an abbreviation for special quasirandom structures. The ...

### Normalization condition in evaluating the radial distribution function for a hard-spheres system

As you suggesting, your computed $g(r)$ goes to zero at large $r$ because of your handling of the periodic boundary conditions. You should include every particle at a distance of $r$ whether it's in ...
Accepted

### How should I generate a radial distribution function (RDF) for an MD trajectory with python?

You could fool the MDAnalysis RDF function InterRDF by setting an artificial cell of a size large enough so that the periodic boundary conditions don't cause any ...

### Radial distribution function for trajectories or time frame?

If I understand your question correctly, you are saying that you have seen cases where time is included in the calculation of the radial distribution function (RDF). The RDF itself does not depend on ...
Accepted

### How do I calculate the radial distribution function from the centre of mass of unit cell in GROMACS?

Here's an approach calculating it by hand with numpy. The coordinates are loaded from the trajectory using mdtraj in python: <...

### How to calculate a structure factor from a radial distribution function?

Without data to test exactly what you are doing it's difficult to say for absolute certain, but it looks to me that your main problem is that your first equation, the equation you are using for your ...

### Compute RDF between COMs of two selections (or groups) using GROMACS

The correct syntax is then the following: ...

### How do you calculate a radial distribution function on a lattice?

As others have commented, discretization does not matter. Below you can see a picture that tries to explain this point. The $\mathrm{d}r$, or more correctly for the approximation we are making the \$\...

### How to calculate displacement in each coordinate and wrap w.r.t. lattice parameter?

Sticking with ase you can use the built-in get_distance function. It supports non-orthogonal unit cells. An example to get the distance between atom number ...

### Have I missed something? RDF (radial distribution) script cannot capture the correct .xyz

Ok, I think I figured out why your code is giving a straight line. This is too big to write as a comment, so I am putting this as answer. At the start of the function, you are determining the edges of ...

### Generating special quasirandom structures (SQS) for surface calculations?

There are two different perspectives here. The first one is the creation of the SQS structure itself accomplished through the ATAT package, for example. The second one is the calculation of the slab ...

### How to quantify the lattice distortion from XRD?

First of all it must be clarified that a lattice is a collection of geometrical point all characterized by a same surrounding (that is, each lattice point has the same number of nearest neighbour ...

### How to calculate displacement in each coordinate and wrap w.r.t. lattice parameter?

Have you tried using the Ovito where there are built in functions to evaluate both RDF and CN of a system? Additionally, it might be possible to use Vesta to convert the unit cell to a rectangular one ...
1 vote

### How to quantify the lattice distortion from XRD?

In my group we develop continuous symmetry and chirality measures that can be used to quantify the distortion of a structure, given the 3D coordinates. Please see: https://csm.ouproj.org.il/ See also ...
1 vote

### Generating special quasirandom structures (SQS) for surface calculations?

As Anibal points in his answer, generating the SQS and using it for a surface calculation are two separate things, and shouldn't affect each other. You would still take all precautions as usual while ...

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