# Tag Info

5

This can be understood from solid-state physics. First of all, for the investigated system with lattice constants $\vec{a}_1,\vec{a}_2$ and $\vec{a}_3$ (length), the reciprocal lattice vectors (1/length) can be calculated as: \begin{align} \vec{b}_1 & = 2\pi \dfrac{\vec{a}_2\times\vec{a}_3}{\Omega} \\ \vec{b}_2 & = 2\pi \dfrac{\vec{a}_3\times\vec{a}...

8

Comparing what each software is capable off, is relative easy: open both webpages and look for feature pages. From SIESTA project page: Total and partial energies. Atomic forces. Stress tensor. Electric dipole moment. Atomic, orbital and bond populations (Mulliken). Electron density. Geometry relaxation, fixed or variable cell. Constant-temperature ...

12

For the "why" you should use the tetrahedron method when computing the density of states, check out this paper on exactly that topic! In short, other approaches (e.g. Gaussian smearing) will occasionally obscure (and artificially introduce) some features of the density of states. As for how the method works, quoting from the paper directly about ...

4

Mastery and minimal effort create a large conflict. It takes significant effort to master a computer language, beyond just learning the syntax. So, I'd first set my expectations that I need to work hard. Next, yes, the previous authors have very sound suggestions and I'll respectfully not repeat them here. One technique I've used in my many decade career (...

1

The best start for learning Fortran it to try to ignore the newer languages you have learned. Fortran is an early language that was very powerful at the time. It is not "Object Oriented" and is not geared for dealing with bits, bytes, addresses. I have taught Assembler, Visual Basic, RPG, PL1, Pascal, Fortran, C, & C++ in colleges. But I will ...

2

Prior to any production calculation, the convergence study with ecutwfc, k-points and ecutrho should be enough. But, the better should be to do a convergence study using the property you are interested in. Please, take a look in previous discussion here, here and here.

5

It all depends on the precision you need for your calculations. One way... From your data, if you are concerning only with energies with only one/two decimal places, your calculation are ok since the first value of ecutoff, 240 (as the first two decimal places remains the same for all other calculations). But if you are interested in energies with four ...

6

Convergence is always defined in term of tolerance what user choose and based on your data, I will take ecutwfc as 70 Ryd. You should also report run time along with these data. For considering ecutrho I will suggest you to stick with default value, if you are dealing with metallic system. Kinetic energy cutoff (Ry) for charge density and potential: For ...

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