The ABINIT Users Mailing List ( CLOSED )

[<David.Paterson@csiro.au>]

I'm a complete novice at ABINIT. My first test gave the wrong bond length for 
NaCl and I need to know why.

My final application will be to use ABINIT to explain why the adhesion force 
between a NaCl crystal and a SiO2 crystal (atomic force microscope with 
controlled low humidity environment) is much greater than between a NaCl 
crystal and a Si3N4 crystal.

ABINIT with .pspgth pseudopotentials gave bond length and energy for diatomic 
NaCl as 2.358 angs -59.75 ha and with .pspnc 2.435 angs -22.89 ha while 
references say bond length should be 2.76 angs ionic or 2.56 angs covalent.

Is the problem:
a) I shouldn't be using diatomic
b) My references are wrong
c) Wrong pseudopotentials
d) Can't use density functional theory on this problem
e) Wrong ecut (I'm using 30)
f) Other

Does ABINIT successfully handle covalent, ionic and intermolecular (H...Cl) 
bonds? Do I need to change the .in file for different bond types?

Do you have a .in file with NaCl, SiO2 or Si3N4 crystals or crystal surfaces?

I've been told that the SiO2 may be coated by OH groups on the Si. Any idea 
what the surface of an Si3N4 crystal is like?

Any advice on how to calculate the number of k points, number of bands?

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Dr David Paterson
David.Paterson@csiro.au

CSIRO Manufacturing & Infrastructure Technology
PO Box 56
Graham Rd, Highett, Vic, 3190
AUSTRALIA

Ph 61-3-9252-6086
Fax 61-3-9252-6244
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