Theoretical X-ray photoelectron spectra of polymers by deMon DFT calculations using the model dimers

Core-electron spectra of 15 polymers [(CH2CH2)(n) (PE), (CH2CH(CH3))(n) (PP ), (CH2CH2NH)(n) (PEI), (CH2CH2O)(n) (PEG), (CH2CH(OCH3))(n) (PVME), (CH2CH F)(n) (PVF), (CH2CF2)(n) (PVDF), (CF2CF2)(n) (PTFE), (CH2CH(CN))(n) (PAN), (CH2C(CH3)(CN))(n) (PMAN), (CH2CH2S)(n) (PETHS), (CH2CHCl)(n) (PVC), (CH2CC l2)(n) (PVDC), (Si(CH3)(2))(n) (PDMS), (Si(CH3)(2)O)(n) (PDMSO)], and valen ce photoelectron spectra (XPS) of the six polymers (PP, PEI, PAN, PMAN, PVM E, PTFE) were obtained by deMon density-functional theory (DFT) calculation s using the model dimers. The core-electron spectra were simulated with the Gaussian lineshape functions with fixed linewidths of 0.5, and 1.0 eV for each C1sd, and (N1s, O1s, F1s) MO value, respectively, and calculated Al-K alpha Valence photoelectron spectra were obtained using Gaussian lineshape functions of an approximate linewidth (0.08I(k)): I-k(I-FL) = I-k' - WD, as indicated in previous works. The vertical ionization potential I-k' and ea ch core-electron binding energy (CEBE) were calculated by restricted genera lized diffuse ionization (rGDI) and unrestricted generalized transition-sta te (uGTS) models, respectively. The theoretical core-electron spectra showe d better agreement with the experimental ones of the polymers than those du e to Koopmans' theorem. The difference between the calculated and the exper imental CEBEs reflected the reasonable WDs of the polymers. (C) 2000 Elsevi er Science B.V. All rights reserved.