Hello everyone.

Our challenge is to build an amorphous polymer matrix of Polyethylene with correct density and zero stresses. (figure 1 - attached below). First we have to construct a periodic cell with 5 chains of PE molecules with 50 repeat units each with initial density 0.1 g/cm3. Then to perform geomtry optimizaitons, NPT, NVT dynamics etc.

But we are facing some basic problems and could not solve them.

1. How to construct a periodic cell with 5 chains of Polyethylene molecules with 50 repeat units each with initial density of 0.1 g/cm3? Which options ( Build/ Modify/ Modules/ Tools ) to use for the construction purposes?

We can build 5 chains with 50 repeat units. ( figure 1, attached below). But we could not put them in a cell. How can we put those 5 chains in a cell ? How to make them periodic?

2. After the construction of the periodic cell, which module can be used to perform geometry optimizations and long time NPT and NVT dynamics?

Please, help us out. We are badly in need of advice.

Regards,

Russell-Siam