Electron-Phhonon Interaction Lab Report

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We now use the method described in Section 2 to studythe effects of electron-phonon interaction on the electronic transport properties of (C60-1X1)2(X=N,B) molecule. We set tC-C=2.5 eV, αC-C=6.31 eV/Å, KC-C=49.7 eV/Å2 [35] tC-B=1.17 eV, αC-B=6.04 eV/Å, KC-B=51.1 eV/Å2,tC-N=1.05 eV, αC-N=6.13 eV/Å, and KC-N=49.6 eV/Å2 [36] and T=300 K in the calculations. The doped atoms are located at about the same distance from each lead and they are indicated with a different color from C atoms in each molecule. (Fig. 1).
We set the coupling strength between the nearest atoms in the electrodes t=1.0 eV and between the molecule and the electrodes tc=1.25 eV according to [37]. The electron-phonon coupling strength D is set to 0.005 eV.
At equilibrium state,
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It is shown that an extra metal atom incorporated in the center of the fullerene molecule can modify the transport through molecule due to the electron transfer from metal atom to the fullerene cage. Since N (B) has one more (less) electron than C, we can substitute one or more carbon atoms of fullerene by N and B atoms to donate electron(s) or hole(s) to the cage.In figures 5 and 6, the current–voltage characteristics of N:N(each of C60 molecules doped with N atom) and B:B (each of C60 molecules doped with B atom) doping is indicated as the bias voltage in the presence and absence of the electron-phonon interaction. The results show that the total current for the doping one N atom in each C60 cage is different from that for the B doping. It is due to the difference ofmolecular energies of (C59B)2 and (C59N)2 molecules. By comparing Figures (5) and (2), it is seen that the current for N:N doping is significantly increased compared to pristine (C60)2 fullerene. In Fig.7 the transmission function curve of (C59N)2 molecule is indicated. It is seen that a high transmission peak is formed at the Fermi level. Because the LUMO level of each C60 molecule is partially filled due to the excess charge of N atom.One might expect that the current increase meaningfully with B:B doping as well as N:N doping.Because B atom has one less electron than C atom, therefore doping one B atom

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