ICHARG

• ICHARG=1

Read the charge density from CHGCAR file, and extrapolate from the old positions (on CHGCAR) to the new positions using a linear combination of atomic charge densities.

In the PAW method, there is, however, one important point to keep in mind: For the on-site densities (that is, the densities within the PAW sphere), only l-decomposed charge densities up to LMAXMIX are written. Upon restart, the energies might, therefore, differ slightly from the fully converged energies. The discrepancies can be large for the DFT+U method. In this case, one might need to increase LMAXMIX to 4 (d-elements) or even 6 (f-elements).

Tip: To improve convergence and reduce the number of electronic steps, it is recommended to set ICHARG = 1 when starting calculations repeatedly with small changes in the input parameters.

: