The ABINIT Users Mailing List ( CLOSED )

[Hongyi Zhao <hongyi.zhao@gmail.com>]

Hi all,

Now, I use the following input file to compulate the optimum interatomic 
distance of two H atoms in H_2 molecular:

-------------
ndtset 21
xcart:  -0.5  0.0 0.0
        0.5  0.0 0.0
xcart+  -0.025 0.0 0.0
        0.025 0.0 0.0
getwfk  -1
nband    1
acell 10 10 10
ntypat 1
znucl 1
natom 2
typat  1 1
ecut 10.0
nkpt 1
nstep 10
toldfe 1.0d-6
diemac 1.0
diemix 0.5
-------------

But I feel so wondering about the following things:

Since the parameter *xcart* has set the positions of H atoms, why should 
I must also give the acell parameter at the same time.  I mean, with the  
the parameter *xcart*, we can already determine the distance between the 
two H atoms.  I've read the abinit's *Complete list of input variables* 
and cann't understand this thing. 

Furthermore, for the case I posted here, it only use the parameter 
acell instead of using it combinating with the parameter *rprim*, why?

Thanks in advance.

Hongyi Zhao
GnuPG DSA: 0xD108493B