next up previous contents
Next: wNGXhalf, wNGZhalf Up: Pre-compiler flags overview, parallel Previous: REAL_to_DBLE (VASP.3.X only)   Contents

NGXhalf, NGZhalf

For charge densities and potentials, half the storage can be saved if one of these flags is used, since

\begin{displaymath}
A_q = A^*_{-q} \quad \mbox{and} \quad A_r = A^*_r.
\end{displaymath} (1)

To use a real to complex FFT you must specify -DNGXhalf for the serial version and -DNGZhalf for the parallel version. If -DNGXhalf is specified for the serial version the real to complex FFT is "simulated" by a complex to complex FFT.

Mind: If this flag is changed in the makefile, recompile all *.F files. This can be done typing


touch *.F
make vasp



Georg Kresse
2009-04-23