Dear Wien2k Prof. Blaha and other Wien2k experts, To put a joint paper on complex Metal-organic halide perovskites, I am trying to reproduce some experimental results measures by my collaborator.
For my complex system, I got low frequency dielectric constant value of ~5.6 and the calculated the exciton binding energy ~0.087 - 0.095 eV (85 -97 meV). This is too high because the measurements here get about 13 meV and a 1-2 transition of ~9.9 meV (measured). I used PBE functional with 4x4x4 k mesh. My band gap is in perfect tune with the experimentally observed band gap (1.57eV). The problem may be that my epsilon value (~5.6) is too low and I looked up our local measured value of ~18 for the low frequency part. If I use this value then much better exciton binding energies come out. What can be an mistake that I may did in calculation? or it may be a reason of the device fabrication because for experimental part some p-i-n and n-i-p type device has been framed. Sincerely Bhamu
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