I am sorry to bother everyone again but there is

a question I can’t understand.

I peformed a MD simulation and PPPM Ewald method

is used to handled the long-range coulomb interactions.

In the PPPM Ewald, the fast Fourier transform (FFT) is

employed and this should cost some time in computing

the long-rang interaction in my opinion.

But, here is the last part of my log.lammps, which

shows the PPP timing information.

PPPM timing info:

Make_rho time = 452.786283392905

Make_rho of long time = 14.4309637768169
Poisson time = 11.3112034606929
Poisson of long time = 0.360504665005105

Electric_field time = 2585.50093744964

Electric_field of long time = 82.4037117327714
Brick2fft time per timestep = 0.000000000000000E+000
Total brick2fft time = 0.000000000000000E+000
Brick2fft of long time = 0.000000000000000E+000

Fillbrick time per timestep = 0.000000000000000E+000

Total fillbrick time = 0.000000000000000E+000

Fillbrick of long time = 0.000000000000000E+000
FFT time per timestep = 0.000000000000000E+000
**Total FFT time = 0.000000000000000E+000**
FFT of long time = 0.000000000000000E+000

In light of above info, I can’not understand why the

'Total FFT time ’ is zero.

DO I have something wrong with the Ewald method ?

Thanks a lot.