ABINIT Discussion Forums

dear abinit users
i want to plot a band structure
my stucture is honeycomb & when i define my structure in hexagonal spacegroup & use
xred
0.333333333333 0.666666666667 0.5000000000000
0.666666666667 0.333333333333 0.5000000000000

in this case my band stucture is true
but when I want to define my structure in P1 i use
xred
0.166666999 0.000000000 0.500000000
0.500000000 0.000000000 0.500000000
0.000000000 0.500000000 0.500000000
0.666666985 0.500000000 0.500000000

my egap is wrong & there is some differences ......
I want to know that when I want to define a structure in P1 what should I do ?

& know I must use P1 .

how can i solve my problem ?
Sincerely
sem .

Not knowing the whole of the input file, it is difficult to tell you why you do not get the same thing. But I notice a few things.

-It seems that the P1 structure is a larger cell structure. In that case, you should get a folder band structure. It will not look the same as the original structure and you will have more bands per k-point. However, you should recognize some features between the two band structure.

-The P1 structure does not have the same lattice vectors as the original (rprim). Since the path of the band structure is given in term of the reciprocal lattice vectors, you have to redefine them to plot the same path.

Lastly, I notice that the xred positions of the P1 structure are not precise, for example you should change 0.666666985 to 0.6666666666. You want to give ABINIT enough digits so that the symmetry can be recognized. In principle, ABINIT symmetry finder should realize that the P1 cell is not the primitive cell and it will advice you to reduce the cell as the calculation can be reduced. If you still want to perform the enlarged cell, you will need to include the chkprim=0.

Michel