Dear PWSCF users and developers, I wish to do a transmission calculation and confused about the input file. I have a question on example 12 of the package, where transmission of monoatomic Al wire with a H atom adsorbed on the side is done. The SCF run in the device region is done with (some part of input file is given below)
&system ibrav = 6, celldm(1) =12.0, celldm(3) =1.875, where the atomic postions of different atoms is Al 0.00000000 0.00000000 0.0000 Al 0.00000000 0.00000000 0.375 Al -0.02779870 0.00000000 .75537515 H 0.19269012 0.00000000 .93750000 Al -0.02779870 0.00000000 1.11962485 Al 0.00000000 0.00000000 1.5 So, looking at the z coordinate of above system, we notice that device region is periodic with period 1.875. So, physically we are solving for an infinite device region, but in the physical setting of a transmission problem leads are semi-infinite and device is finite. Shouldn't we use some kind of vacum, i.e. taking 3rd lattice vector large, which effectively would represent the finite device region? Also how much part of the leads should be taken as part of device region, Is there some kind of convergence criterion? Is it like keep increasing part of lead in the device reion till further increase does not substantial change device behavior, e.g. Bloch's state? Regards, Manoj Srivastava Ph.D. student Department of Physics University of Florida, Gainesville, FL