I'm using Burai, the gui version of Quantum Espresso to carry out SCF calculations for a material. I followed the excellent tutorial series from here which carries out the calculations on the silicon example that comes with Burai. I was able to replicate the results successfully. For my own mater...

I am currently working with a perovskite material which shows forbidden transitions. Older studies used bigger values of $\alpha$ in HSE06 calcualtions(to match with experimental Band Gap) but a recent study showed that this is not the case. Rather the electronic BG is around 0.98 and optical one...

I have a 3D charge density file, calculated from Quantum Espresso DFT. If someone calculates the total charge (number of electrons) of an unit cell from that cube file (using a numerical approximation method, for example, a spherical integration), what should be the basic mathematical equation to...