3 Jul 2002 03:37
Re: Using mpb for quasiperiodic lattices
Orion Crisafulli <orion <at> phys.hawaii.edu>
2002-07-03 01:37:12 GMT
2002-07-03 01:37:12 GMT
Hi, I was wondering about using mpb to compute the band structures for quasiperiodic lattices, in addition to periodic ones. It looks like mpb usually takes as its input up to 3 lattice vectors, and then generates a (infinite?) lattice for the calculation. The exception seems to be when, say, you're trying to find a state in a point or line defect in your lattice, and you need to create a supercell of finite size around the lattice. Is this generally true? By the way, is there any limit to the size of a supercell you could create around, say, a square lattice of dialectric rods in 2-D (I think the example on the web has 5 x 5 rods--could you make this, say, 50 x 50 rods if you wanted, or would it be even worth it, and how could you tell?) A quasiperiodic crystal is specified by more than 3 integer linearly independent basis vectors in 3-D, and more than 2 integer linearly independent basis vectors in 2-D. I've got a program that generates these crystals (it takes as its inputs the kind of lattice geometry you want, specified by the basis vectors and lattice size, and outputs the lattice vertices), and I was wondering: would it be possible to get mpb to read in all the vertices and place objects at them (say spheres, or cylinders), and then compute the band gaps? Would there be some "non-tedious" way for these vertices to be entered in to a list, or would I have to say, "(make sphere (center x y z)" for each vertex? The other thing I was thinking about was modifying mpb so that it could handle more basis vectors and generate quasiperiodic structures, but I'm getting the feeling that this wouldn't be too easy, is that right? I had another question: I saw in the data tutorial on the web the example of making a diamond lattice of spheres, and finding the(Continue reading)
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