output of velocity profile

Dear all:

In the lammps package, it has the in.nemd code, which could run NEMD simulation for a 2d system without problem. After implementing codes to output off-diagonal stress tensor (p_xy and so on), and velocity profile ( in order to calculate the slope of velocity), I can see that it still worked well. But the velocity profile showed the information like following:

Spatial-averaged data for fix 3 and group all

Timestep Number-of-bins

Bin Coord Ncount vx vz

1000 1
1 0.5 160 0.180098 0
2000 1
1 0.5 160 0.241645 0
3000 1
1 0.5 160 0.309612 0
4000 1
1 0.5 160 0.355982 0
5000 1
1 0.5 160 0.388848 0
6000 1
1 0.5 160 0.434107 0
7000 1
1 0.5 160 0.473058 0
8000 1
1 0.5 160 0.502047 0

So it only has one bin and only one velocity data. Then how to calculate the velocity slope? Is there any way to modify the in.nemd file so that it can output more vx data in one timestep? Thanks a lot.

Laura

The legend for the file is saying that # of bins = 1.
That is something you choose with the fix ave/spatial command. Define
more bins and you will get more output.

Steve