The ABINIT Users Mailing List ( CLOSED )

["Chun Li " <chun.li@mf.mpg.de>]

Dear Abiniters,

 

I have some basic questions about the input variables:

 

1)       Is there certain physics meaning about acell? Many examples use the value of the crystal constant. However, if there are two crystal constants (a and c), which one should we use?

2)       If I have defined the xcart, Must I also provide xangst, acell, and rprim? And should the origin of the coordinates I defined be the same as the origin of the primitive vectors? That is, should the values of xcart be relative with the values of rprim (if rprim should also be defined)? I almost confused about the following variables: xcart, xangst, xred, acell, rprim, and rprimd.

3)       If the crystal is composed of two kinds of atom, I want to define a unit cell containing 20 atoms, then how can I setup the periodical boundary conditions to perform simulations? I have not found relative example in the tutorial.

 

I am a freshman and need your help, thanks a lot.

Best regards.

 

Chun Li