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I'm working on Graphene so I'm using a 2 atom unit cell that produces a hexagonal structure. Here is the input file that produces the hexagonal geometry of Graphene

# Hexagonal Structure Graphene
#

# Definition of the Hexogonal unit cell
# d = 2.4612 Angstrom = 4.650615 Bohr

# a1 = (3/2)d x_hat - (sqrt(3)/2)d y_hat
# a2 = (3/2)d x_hat + (sqrt(3)/2)d y_hat

acell 1 1 1
rprim 6.9759225 -4.027550733 0.00000000
6.9759225 4.027550733 0.00000000
0.000000000 0.000000000 24.00000000

ntypat 1 # There is only one type of atom
znucl 6

Chksymbreak 0

ixc 11

prt1dm 1

natom 2 # There are two atoms
typat 1 1
xangst
2.4612 0.00 0.00
4.9224 0.00 0.00

My question is how one inputs the rprim vectors. In this file I've entered the rprim vectors as row vectors. My visualization tools (Venus/Vesta and Jmol) show that this produces the correct geometry however the manual seems to indicate that rprim vectors should be input as column vectors. When I do input them as column vectors the geometry is all wrong. Can anyone say what is going on here?

Also I need guidance regarding what pseudopotential should be used with what exchange functional. I've not a clue. Any help would be appreciated. Thanks.



kptopt 1
ngkpt 12 12 2
nshiftk 4
shiftk 0.5 0.5 0.5
0.5 0.0 0.0
0.0 0.5 0.0
0.0 0.0 0.5

nstep 20

optforces 1

ecut 15

# SCF definition
iscf 2
diemac 12.0
nsppol=1
toldfe 1.0e-08

According to the documentation:

the primitive vectors a1,a2, a3, which are R1p, R2p, R3p below are obtained as:
rprimd

This internal variable gives the dimensional real space primitive vectors, computed from acell, scalecart, and rprim.

R1p(i)=rprimd(i,1)=scalecart(i)*rprim(i,1)*acell(1) for i=1,2,3 (x,y,and z)
R2p(i)=rprimd(i,2)=scalecart(i)*rprim(i,2)*acell(2) for i=1,2,3
R3p(i)=rprimd(i,3)=scalecart(i)*rprim(i,3)*acell(3) for i=1,2,3


you could check out this operation to see if you obtain the correct primitive vectors.
Note that scalecart=1

Best
Tonatiuh Rangel

Dear Abinit User

I want to define Graphene Nanoribon lattice in Abinit, but since i am beginer i don know how i shoul do this.

You do favor if You give me a sample file for using as sample.

Sincerely Yours

Riemann