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5 votes

In solids physics, how are Van Der Waals forces modelled?

The documentation for pw.x, version 7.2, lists several different ways to compute van der Waals corrections: Grimme's semiempirical DFT-D2 and DFT-D3; Tkatchenko–...
elutionary's user avatar
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5 votes

Negative band gap in DFT calculations

Some materials erroneously give a metallic state even if it isn’t. Depending on what type of material and exchange-correlation functional you use, this can be more or less likely to happen. With ...
AGS's user avatar
  • 1,141
3 votes

Can conventional unit cell have higher symmetry than primitive cell for the same crystal?

A primitive and conventional cell don't have different symmetries. The primitive cell is a Wigner-Seitz cell of the same Bravais lattice; the primitive cell is the smallest choice, but the ...
Tyler Sterling's user avatar
3 votes

What is the Herman-Skillman method?

In Herman and Skillman method - numerical methods were performed for self-consistent field calculations based on simplified model of Slater’s version on Hartree-Fock equations for one electron wave ...
epsilon02fft's user avatar
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2 votes

How to interpret defect formation energy diagram?

Why defect formation energy is plotted against $E_F:$ Let's go step-by-step. First, let us look at the Defect Formation Energy (DFE) formula: $$ E_f^D(q,E_F) = E^D(q)-E^{\mathrm{host}}-\sum n_i\mu_i + ...
Abdul Muhaymin -Free Palestine's user avatar
1 vote

Introducing a vacuum space in z direction for 2D monolayer calculations

As your system will be only periodic in 2D, yes, you need to add a vacuum layer (in both sides of your layer) to avoid image interactions. The ideal way to do this is running a convergence test where ...
Camps's user avatar
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