[xcrysden] Fermi surface for FCO

[Eyvaz Isaev]

Dear Tone,

Thanks for your explanation. Actually, I have checked
BZ for base centered  orthorhombic lattice and it
looks like BZ for HCP structure, but with different
symmetry points, and probably, with inequal hexagon
sides. Yes, sure, I checked it according
Bradly&Cracknell's textbook (p.98). 

Now I am completly agree with you, and glad that
XCrysDen works properly. 

Best regards,
Eyvaz.

--- Tone Kokalj <tone.kokalj@ijs.si> wrote:

> > Dear Tone,
> >
> > b/a and c/a in my calculations are far from those
> for
> > HCP structure.
> 
> On the contrary, your lattice vectors are very
> compatible to those for
> hexagonal structure. Your primitive lattice vectors
> (in ANGSTROMS) are:
> 
>  PRIMVEC
>    1.3070671900     2.3643091383     0.0000000000
>   -1.3070671900     2.3643091383     0.0000000000
>    0.0000000000     0.0000000000     2.9142197535
> 
> These are indeed as you indicated:
> 
> > Basis vectors BCO (nbrav=9) lattice read from
> INPUT_PW
> >
> >   a/2  b/2  0
> >  -a/2  b/2  0
> >    0    0   c
> 
> But look at above numbers: the angle between a and b
> vectors is 122.1
> deg (57.9 deg), while the other angle is 90 deg.
> This is quite close
> to hexagonal lattice.
> 
> The primitive reciprocal vectors are (ANGSTROMS^-1):
> 
>  RECIP-PRIMVEC
>     0.3825358052    0.2114782674    0.0000000000
>    -0.3825358052    0.2114782674    0.0000000000
>     0.0000000000    0.0000000000    0.3431450216
> 
> These are again as you indicated:
> 
> 
> > and so basis vectors in the reciprocal space are
> >   1  1/(b/a) 0
> >  -1  1/(b/a) 0
> >   0    0     1/(c/a)
> >
> 
> Indeed, the BZ for this vectors will be very close
> to that of
> hexagonal structure. As you can see from the top
> side figure (bz.png),
> there is a hexagon, but with the angles 118.9 and
> 122.1 deg!!!
> 
> What is strange with your data is your structure:
> the side view
> (struct-side.png) reveals an awkward structure with
> very close
> inter-atomic distance between the two Cu atoms: is
> this really the
> right structure?
> 
> On the other hand, if you compare the figures
> struct-top.png and
> bz.png, you will notice they are compatible.
> 
> Best regards, Tone
> 


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