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.

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27
votes
1answer
438 views

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 ...
30
votes
3answers
585 views

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, ...
20
votes
3answers
395 views

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 ...
18
votes
1answer
646 views

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. ...
14
votes
3answers
391 views

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 ...
10
votes
1answer
82 views

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 ...