[QE-users] Consequence of incorrect setup of electron configuration.

[Evgeny Permyakov]

Disclaimer: I'm a user of QE with moderate basis in computational
chemistry. I have very basic understanding of math behind pw/dft
setup. If some part of the theory is critical for understanding the
answer to my question, please point at it.

Questions:
I run into situation where I have to estimate errors arising from
incorrect setup, specifically

1. Let's consider a supercell with odd number of electron with
nspin=1 (non-polarized calculation). The result should probably be
incorrect, but how would the error manifest? I'm specifically
interested in errors for electron state structure and total energy.

2. Let's consider a supercell A which is a half of supercell B. A
calculation with supercell B reveals a band with electron population
of 1 electron /per B (the system is paramagnetic and the calculation
uses nspin=2). Would a band with close energy manifest for a run with
supercell A ?

for the purpose of the questions let's assume that only single-point
calculations were performed.