Hi guys,
I want to know how to difine an ellipsoidal region in LAMMPS. I know the "region" command can only difine block, sphere, cylindrical, cone,.... However, I am wondering is there some other packages that can do this kind of CAD work, i.e., to define a region with arbitrary geometry.
Br,
Kai
I don't know about programs, but in LAMMPS you can do it hard way by creating a lot of spherical regions and unite them into one ellipsoidal region.
If you want to just create atoms in shape of ellipsoid then you can use command create_atoms. There is possibility of creating atoms with coordinates satisfying equations which you can define.
In current version of LAMMPS it may not be possible at this moment unless you add this feature in the code. In another code :LIGGGHTS (which is an extension of LAMMPS for granular materials), you can use geometric mesh (e.g. STL file) to define specific walls/regions with any shape. You may want to look into that.
It's quite easy to implement your idea. Just PROGRAM FOR YOURSELF to make input data which includes atom position, atom type and so on. The format of LAMMPS readable data is defined under the entry of "read_data". You can easily define any shape of region in your own program and atom type within this region should be different from out-this-region. In addition, you should be careful when you define pair coefficients.
You can also define a region by its analytical description. i.e. using a variable in a inequation. Then you can define a group using "if's"
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