Dear BingHuang, Argo, Thank you for your quick response. We know that the physical features of the bands should be same for both unit cell and supercell. But for a semiconductor, I have found that, the bandgap shifted from M point to Gamma point when we consider 2*2 supercell (but the band gap value is same for both unit cell and super cell).
Do you think it is expected? I am confused. Could you please help me? Thanks in advance, Barnali Bhattacharya, Assam university,India On Tue, Mar 17, 2015 at 6:41 AM, BingHuang <hbdft2...@gmail.com> wrote: > Hi, > > The band structure of 2x2 supercell is definitely different from that of > 1x1 unit cell. In the supercell case, band structure is folded. Please > have a look at the article "EPL, 107 (2014) 27006" ( > http://iopscience.iop.org/0295-5075/107/2/27006) > > Best regards, > Bing > > ------------------------------ > From: argo.nurbaw...@gmail.com > To: siesta-l@uam.es > Date: Mon, 16 Mar 2015 18:11:57 +0800 > Subject: Re: [SIESTA-L] Band structure calculation > > > Hi Barnali > > your structures are different from one another. > > In your unit cell structure C-C bond is 1.56 Ang, while in your 2x2 > supercell the C-C bond is 1.42 Ang. > > You need to relax the structure correctly first (together with the lattice > vectors), then the two bands should be the same. > > Good luck. > > Argo. > > On Mon, 2015-03-16 at 15:15 +0530, Barnali Bhattacharya wrote: > > Dear all, > > I have calculated the band structure for graphene unit cell containing two > atoms which is accurate one. But when I am trying to calculate the band > structure of 2*2 graphene super cell the band structure look different . > But this should not be expected, because the band structure for unit cell > and super cell should be same. > > Could anybody guide me why I get different band structure for same system > (unit cell and supercell)? > Could anybody help me to solve this problem? > > > > Here I have attached the input file for graphene unit cell and graphene > 2*2 super cell for detils information and the jpg file. > > > Thanks in advance, > Barnali Bhattacharya, > > Assam university,India > >
