Default: | |

if ISTART=0 | 2 |

else | 0 |

**0**-
Calculate charge density from initial wave functions.
*Mind:*if ISTART is*internally reset*due to an invalid WAVECAR-file the parameter ICHARG will be set to ICHARG=2. **1**- Read the charge density from file CHGCAR, and extrapolate from old positions to new positions using a linear combination of atomic charge densities
**2**- Take superposition of atomic charge densities
**+10**- non-selfconsistent calculation

Adding ten to the value of ICHARG (e.g. using 11,12 or the less convenient value 10)
means that the charge density will be kept constant during the *whole electronic
minimization*.

There are several reasons why to use this flag:

- ICHARG=11: To get the eigenvalues (for band structure plots), eigenfunctions or the DOS for a given charge density taken from CHGCAR. CHGCAR can be obtained from a selfconsistent calculation for a smaller k-points set see section 11.3.
- ICHARG=12: Non-selfconsistent calculations for a superposition of atomic charge densities. This is in the spirit of the non-selfconsistent Harris-Foulkes functional. The stress and the forces calculated by VASP are correct, and it is absolutely possible to perform an ab-initio MD for the non-selfconsistent Harris-Foulkes functional (see section 9.3).

The initial charge density is of importance in the following cases:

- If ICHARG>10 the charge density remains constant during the run.
- For all algorithms except IALGO=5X the initial charge density is used to set up the initial Hamiltonian which is used in the first few (NELMDL) non selfconsistent steps.

Mon Mar 29 10:38:29 MEST 1999