Suman, What I use to do is to transform (rotate/translate) the XYZ coordinates of my system in such a way that the central point of it correspond with the point (a/2, b/2, c/2). Where a, b and c are the fake lattice parameters. These lattice parameters have to be big enough to avoid disk-disk interaction. This "big enough" could be determined by calculating the system energy for different values of the lattice parameters. When the system energy become lattices independent, that are your 'big enough" values.
In your case, as you have a disk (of radii R and width r, for example), you can start with lattice parameters a=b=c=2R. This is the easy way where you have the same lattice size in three directions. This can imply a waste of resource. As R >> r, the lattice parameter perpendicular to the plane do not need to be the same as in the other two directions. An important point is that the coordinates must be Cartesian. If you use fractional coordinates, the atoms position will scale as you change your lattice coordinates. []'s, @mps On Fri, Feb 7, 2014 at 1:54 PM, Suman Chowdhury <[email protected]>wrote: > Thanks to all.Can you tell me how I put "fake boundary condition" i.e. > putting the nano disk in a large enough box.. > > > On Fri, Feb 7, 2014 at 9:11 PM, Bailey, Steven > <[email protected]>wrote: > >> Taking the isolated disc will give you the energy levels (flat). You >> need to connect the disc to periodic leads or make the discs periodic to >> obtain the band structure of your system. >> >> >> >> Dr S Bailey >> >> Department of Physics >> >> Lancaster University UK >> >> Email: [email protected] >> >> Tel: +441524592844 >> >> >> >> *From:* [email protected] [mailto:[email protected]] *On >> Behalf Of *Suman Chowdhury >> *Sent:* 07 February 2014 15:19 >> *To:* [email protected] >> *Subject:* [SIESTA-L] Nanodisks >> >> >> >> Dear all, >> >> How do I calculate the electronic structure of graphene nano disks which >> do not have any boundary condition by siesta? >> >> >> >> -- >> >> >> >> >> *Junior research fellow Dept. of Physics, University of Calcutta >> Kolkata- 700009, West Bengal, India.* >> >> * Ph no-+91-9830512232 <%2B91-9830512232>* >> >> >> > > > > -- > > > > *Junior research fellow Dept. of Physics, University of Calcutta Kolkata- > 700009, West Bengal, India.* > * Ph no-+91-9830512232 <%2B91-9830512232>* > >
