[DFTB-Plus-User] Optimization of zwitterion in vacuum

[Alessandro Pirrotta]

Dear all,

I am using DFTB+NEGF. The system I am studying is formed by a molecular
junction with gold electrodes where the device region is formed by three
molecule, one of these is a zwitterion aminoacid. The SC NEGF calculation
does not converge, ergo I cannot trust the transmission I get.

I tried to optimize the aminoacid in vacuum and the C-C bond between the
carboxyl group and the alpha carbon has a length of 2.3 Å in the optimized
structure (way too long).

Does anyone know how to get around this problem? I am only interested in
getting the transport calculation to work properly.

Thanks,
Alessandro

*Alessandro Pirrotta*
PhD student



*Faculty of Science*
Department of Chemistry &
Nano-Science Center
University of Copenhagen
Universitetsparken 5, C321
2100 Copenhagen Ø
Denmark

DIR +45 21 18 11 90
MOB +45 52 81 23 41

alessandro.pirrotta at chem.ku.dk

www.ki.ku.dk
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