[Pw_forum] Which coordinates of K point should be used, referencing to reciprocal CONVENTIONAL vectors or reciprocal PRIMITIVE vectors?

[Stefano de Gironcoli]

for certain bravais lattice (notably the cubic ones) XCrysDen sometime 
recognizes the conventional unit cell (the cube).
pw always works in the primitive unit cell, the one defined by the 
fundamental lattice vectors.

Beware that this depends on your input.
if you define an FCC crystal using a SC Bravais lattice and putting 4 
atoms in the unit cell the BZ displayed is going to be the one for SC

stefano

On 06/29/2011 02:30 PM, Hongsheng Zhao wrote:
> On 06/29/2011 02:29 PM, Paolo Giannozzi wrote:
>> On Jun 29, 2011, at 2:16 , Hongsheng Zhao wrote:
>>
>>> >  For a set of lattice vectors used for our supercell, the 
>>> corresponding
>>> >  reciprocal  vectors may have two different forms:
>> no, the three vectors that generate the reciprocal lattice are uniquely
>> determined by the three lattice vectors that generate the lattice:
>> b_i =  2pi (a_j x a_k)/(a_1 . a_2 x a_3)
>
> From the k path selection function of xcrysden, for specific lattice, 
> you can see two options in the band path selection panel: Primitive 
> Brillouin Zone and Conventional Brillouin Zone. If only one set of 
> unique  reciprocal vectors was generated for three real lattice 
> vectors, what is the difference between Primitive Brillouin Zone and 
> Conventional Brillouin Zone?
>
> Attached please find the the BZ for Si from within xcrysden, could you 
> please give me some hints?
>
> Regards.
>
>
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