The memory requirements of VASP can easily exceed your computer facilities. In this case the first step is to estimate where the excessive memory requirements come from. There are two possibilities:

- Storage of wave functions:
All bands for all k-points must be kept in memory at the same time.
The memory requirements for the wave functions are:
NKDIM*NBANDS*NRPLWV*16

The factor 16 arises from the fact that all quantities are COMPLEX*16. - Work arrays for the representation of the charge density,
local potentials, structure factor and large work arrays:
A total of approximately 8 arrays is allocated on the second finer grid:
4*(NGXF/2+1)*NGYF*NGZF*16

Once again all quantities are COMPLEX*16.

For a more accurate calculation of the memory requirements use the following sheet:

MPLWM = NGXF*NGYF*NGZF/2 or | ||

MPLWV = NGX *NGY *NGZ | ||

LMDIM | ||

NIOND*LMDIM | ||

IRMAX | ||

NRPLWV | ||

NIOND | ||

NBANDS | ||

minimal alloc (NEDOS=300) | 4-10 Mbytes | |

arrays on large grid | ( 5 + NTYP )*MPLWVM*16 | |

arrays on small grid | 3.5 *MPLWV *16 | |

wavefunctions | (NRPLWV+2*NIOND*LMDIM)*(NBANDS+IADD)*IG | |

real space projectors | IRMAX*(LMDIM+2)*NIOND*8 | |

rotation matrizes | 3*NBANDS*NBANDS* IG | |

total | ||

IG=16 | for COMPLEX version |

IG=8 | for gamma point only version |

IADD= 2 | without residual minimization, 10 with residual minimization |

arrays on large grid:

CHTOT, DENCOR, CHTOTL, (CHGGA,CVTOT), CSTRF(NTYPD)

CWORK1, CWORK2

arrays on small grid

CHDEN, CV, CWORK3, CWORK4

wavefunctions

CPTWFP, CPROJ, CPROTM

real space projectors

RPROJ, CRREXP

rotation matrices

CHAM,(COVL,CTMP),CHAMIN

(..,..) means equivalence

In vasp.4.4 the memory requirements can be also calculated
by the `makeparam` utility, which is supplied in the vasp.4.4
directory. It can be created by typing

> make makeparamin the vasp.4.4 directory.

Mon Mar 29 10:38:29 MEST 1999