molecualr dynamics simulation of nanowires

[Ricky]

Hi, I have spent several months learning molecualr dynamics simulation. And I think I have got a good result on the bulk material with my own C++ code. But I failed when I tried to do something in the nanoscale. For example, from BaTiO3 bulk to BaTiO3 nanowires, I think the difference between them is

1. the periodic replicas of the wires are separated by vacuum in the radial direction.

2. there are two kind of nanowires, BaO terminated and TiO2 terminated.

what's more, the ensemble is NPT, with rescaling constant-voltage method and Berendsen constant-temperature method.

 

then, i found that the size of the radial direction became smaller and smaller.

 

am i wrong?