Questions tagged [periodic-system]

Refers to a model which is treated as infinitely repeating, for example so as to use plane-wave basis functions and capture long-range electrostatic interactions.

Filter by
Sorted by
Tagged with
28 votes
1 answer

How accurate are the most accurate calculations?

Taking into account the fact that the theory of quantum gravity does not exist and the QED calculations are not possible for most realistic chemical systems, what levels of accuracy can we expect from ...
Roman Korol's user avatar
  • 1,073
34 votes
3 answers

What are the positives and negatives of periodic DFT codes that don't use plane-wave basis sets?

Most periodic density functional theory (DFT) codes use plane-wave basis sets in conjunction with three-dimensional periodic boundary conditions. In contrast, for molecular systems of finite size, ...
Andrew Rosen's user avatar
  • 7,281
23 votes
1 answer

Why is the band structure of a supercell more dense than for simple cell?

In order to do DFT calculations of metallic alloys, the start point is a supercell, whose atoms are changed to match the desired stoichiometry. Gold and Silver, for example, both have FCC structure. ...
Anibal Bezerra's user avatar
23 votes
3 answers

How to do periodic DFT calculations using Quantum ESPRESSO?

I have only done quantum mechanical computations using non-periodic wavefunctions. I'd like to try to periodic-wavefunction density functional theory. Quantum ESPRESSO seems like a good package ...
Cody Aldaz's user avatar
  • 7,957
16 votes
3 answers

When do I use the lattice parameters obtained computationally vs experimentally?

I have been trying to simulate the properties of Bi2Se3. But the lattice parameters given in Materials Project (which I believe is obtained computationally) is inconsistent with that of experimental ...
Ashique Lal's user avatar
  • 1,581
11 votes
1 answer

Pattern X-Ray Diffraction Fitting

Assuming I have an experimental powder XRD spectra and I have a number of computational structures without any knowledge of which is correct, how can I simulate the powder XRD spectra? Once I have ...
Tristan Maxson's user avatar
4 votes
2 answers

What is the difference between a "periodic image" and a "nearest image" in MD simulation?

As far as I understand - In MD, when a particle or coordinate moves beyond one face of the simulation box, it reappears on the opposite face as if the box were replicated infinitely in all directions....
user366312's user avatar
  • 2,352