Hi Hongsheng,
The difference is 2*pi, I guess it is just a matter of convention.
Regards
jia
On Tue, Jun 28, 2011 at 9:22 AM, Hongsheng Zhao <zhaohscas at yahoo.com.cn>
wrote:
> Dear Prof. Tone and others,
>
> I use pre-compiled xc-1.5.24-linux_x86-semishared.tar.gz on my Debian box.
>
> Now I use the k-path selection function to prepare k-point file used for
> pwscf. ?My system is graphene. ?The graphene.inp file is as follows:
>
> -------------
> ? ? &CONTROL
> calculation = 'scf'
> prefix='graphene'
> pseudo_dir = './'
> outdir='./'
> tstress=.true.
> tprnfor = .true.
> forc_conv_thr=1.0d-4
> nstep=200
> /
> ? ? &SYSTEM
> ibrav=0
> celldm(1)=1.889726
> nat=2
> ntyp=1
> ecutwfc=36
> /
> ? ? &ELECTRONS
> mixing_beta=0.7
> conv_thr = ?1.0d-8
> electron_maxstep=200
> /
> ? ? &IONS
> trust_radius_max=0.2
> /
> ? ? &CELL
> cell_dynamics='bfgs'
> /
> ATOMIC_SPECIES
> ? ?C ?12.0110 ? C.UPF
>
> CELL_PARAMETERS (alat)
> ? ?2.1314617179 ? -1.2306000020 ? ?0.0000000000
> ? ?0.0000000000 ? ?2.4612000040 ? ?0.0000000000
> ? ?0.0000000000 ? ?0.0000000000 ? 36.9180000600
>
> ATOMIC_POSITIONS (crystal)
> ?C ? ? ? 0.000000000 ? ? 0.000000000 ? ? 0.000000000
> ?C ? ? ? 0.666666671 ? ? 0.333333335 ? ? 0.000000000
> K_POINTS {automatic}
> ?4 4 4 ?1 1 1
> -------------
>
> I select the k-path as M --> G -->K --> M , and then generate the
> corresponding files, i.e., ?graphene.pwscf and supportInfo.kpath.
>
> In the file supportInfo.kpath, you can find the following information:
>
> -------------
> ? ?Selected k-points in CARTESIAN coordinates:
> ? ? ? 0.23458 ? ?0.00000 ? ?0.00000 ? ?M
> ? ? ? 0.00000 ? ?0.00000 ? ?0.00000 ? ?G
> ? ? ? 0.23458 ? ?0.13543 ? ?0.00000 ? ?K
> ? ? ? 0.23458 ? ?0.00000 ? ?0.00000 ? ?M
>
> ? ?Selected k-points in crystal coordinates:
> ? ?(with respect to RECIPROCAL-PRIMITIVE vectors)
> ? ? ? 0.50000 ? ?0.00000 ? ?0.00000 ? ?M
> ? ? ? 0.00000 ? ?0.00000 ? ?0.00000 ? ?G
> ? ? ? 0.33333 ? ?0.33333 ? ?0.00000 ? ?K
> ? ? ? 0.50000 ? ?0.00000 ? ?0.00000 ? ?M
>
> ? ?Selected k-points in crystal coordinates:
> ? ?(with respect to RECIPROCAL-CONVENTIONAL vectors)
> ? ? ? 0.50000 ? ?0.00000 ? ?0.00000 ? ?M
> ? ? ? 0.00000 ? ?0.00000 ? ?0.00000 ? ?G
> ? ? ? 0.33333 ? ?0.33333 ? ?0.00000 ? ?K
> ? ? ? 0.50000 ? ?0.00000 ? ?0.00000 ? ?M
> ---------------
>
> Here, I have some puzzles on the k-points in CARTESIAN coordinates obtained
> by XCrySDen. ?For example, the K point in BZ has the fractional coordinates
> as this: ( 0.33333 ? ?0.33333 ? ?0.00000 ).
>
> And in my case, I've the lattice vectors as follows:
>
> ----------
> CELL_PARAMETERS (alat)
> ? ?2.1314617179 ? -1.2306000020 ? ?0.0000000000
> ? ?0.0000000000 ? ?2.4612000040 ? ?0.0000000000
> ? ?0.0000000000 ? ?0.0000000000 ? 36.9180000600
> -----------
>
> So, I can obtain the reciprocal lattice like this:
>
> B ^ T = 2*Pi* A ^ (-1), ?where, A and B are 3*3 matrix whose column vectors
> ?are corresponding to the real space lattice vectors and reciprocal lattice
> vectors, respectively.
>
> Thus, I obtain B as follows from within matlab:
>
> ?>> ?B= 2*pi*inv([2.1314617179 ? -1.2306000020 ? ?0.0000000000;
> ? ?0.0000000000 ? ?2.4612000040 ? ?0.0000000000;
> ? ?0.0000000000 ? ?0.0000000000 ? 36.9180000600])'
>
> B =
>
> ? ? 2.9478 ? ? ? ? 0 ? ? ? ? 0
> ? ? 1.4739 ? ?2.5529 ? ? ? ? 0
> ? ? ? ? ?0 ? ? ? ? 0 ? ?0.1702
>
> So the CARTESIAN coordinates for K point ( 0.33333 ? ?0.33333 ? ?0.00000 )
> should be:
>
> ?>> [0.33333 ? ?0.33333 ? ?0.00000]*B
>
> ans =
>
> ? ? 1.4739 ? ?0.8510 ? ? ? ? 0
>
> As you can see, your XCrySDen gives the CARTESIAN coordinates for K point (
> 0.33333 ? ?0.33333 ? ?0.00000 ) as follows:
>
> ? ? ? 0.23458 ? ?0.13543 ? ?0.00000 ? ?K
>
> I cann't figure out what's the reason. ?Could you please give me some hints
> on this issue?
>
> Attached please find all the files mentioned above.
>
> Regards.
> --
> Hongsheng Zhao <zhaohscas at yahoo.com.cn>
> School of Physics and Electrical Information Science,
> Ningxia University, Yinchuan 750021, China
>
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>
--
Jia Chen
