Deepak, If it's graphene, then none of the results are correct - graphene doesn't have a gap, as I have already told you in a previous email.
Marcos On Wed, Sep 22, 2010 at 4:02 PM, deepak srinivasan <[email protected]>wrote: > > > *2010/9/21 Marcos Veríssimo Alves <[email protected]> > * > >> *Zhendong,* >> * >> * >> *Supposing that you want to plot the wavefunctions corresponding to the >> HOMO and LUMO (you don't make it very clear), what you want is in either the >> WF files or the LDOS file. The easiest thing to do is:* >> * >> * >> *1) Open the EIG file, and check where the Fermi level, EF is.* >> *2) Since you have (I suppose) a molecule, the HOMO will be the energy >> level right below EF, and the LUMO will be the energy level right above EF. >> Take note of those energy levels.* >> *3) You can obtain a spatial distribution of charge for the HOMO and LUMO >> by calculating the LDOS around the levels that you have just obtained. Since >> you have something only at Gamma anyway, your wavefunctions will be real and >> the LDOS will be closely related to them. However, if you need phases and >> signs of the wavefunctions, then you have to really plot the wavefunctions >> themselves - I have never done it, but the manual should provide you with >> sufficient information.* >> * >> * >> *If you decide to calculate the LDOS, be careful to NOT set the energy >> range in such a way that it goes below beyond {E[HOMO] + E[HOMO-1]}/2 (or >> {E[LUMO] + E[LUMO+1]}/2).* >> * >> * >> *Marcos* >> >> >> >> >> > when i try the same for a planar graphene structure of 2.5 nm by 2.5 nm > (having around 250 atoms) i get a band gap of 0.06 eV(HOMO LUMO method) > while if i plot the band structure using gnubands i get a band gap of 0.41 > eV. Why is there a difference and which method is correct > > > -- > regards > deepak > 3rd Year Under Graduate > Electronics Design and Manufacturing > IIIT (D&M),Kancheepuram > IIT Madras Campus,Chennai >
