Dear PWSCF users and developers, I have been trying to understand the PWCOND code for transmission calculation, basically 'transmit.f90' file. The wavefunction in the left lead, right lead and scattering region is given by - psi_k+sum_{k'}r_{kk'}psi_k' psi= sum_{n} a_n psi_n+ sum_{\alpha l m} C_{\alpha l m}psi_{\alpha l m} sum_{k'}t_{kk'}psi_k'
The above expression is from Choi & Ihm's paper, on which I believe PWCOND is based on. Now undetermined coefficients in above expression are r_{kk'}, a_n, C_{\alpha,l,m}, t_kk'. I am confused on code evaluates these coefficients. My understanding is you first get the wavefunction in the leads and then solve scattering region the same way to get the wavefunction in scattering region, so at this point you have already determined a_n and C_{\alpha,l,m}. At last do boundary matching condition between leads and scattering region to get reflection and transmission coefficient. Am I right? My thinking is based on simple quantum mechanics scattering problem where we solve schrodinger's equation in each region and then do boundary matching to get reflection and transmission coefficients. Now looking at the subroutine 'transmit.f90', this does not appear to be the case. It seems as if we are solving the Schrodinger's equation in the scattering region and doing boundary matching at the same time. Using a big matrix and solving something like AX=B. Would anybody mind explaing what's going on in subroutine transmit.f90? Regards, Manoj Srivastava Physics Graduate Student University Of Florida, Gainesville, FL