Cd6Se6 2.699 / 2.862 (2.670 / 2.864) 3.14 (3.14) Cd13Se13 2.710 / 2.801 (2.704 / 2.785) 3.06 (2.99) Figure .3: Absorption Peak of Cys-capped Cd33Se33. Left: Experimental result ; Right: Simulation Estimation. Simulation Results Bare Quantum Dots In this section, we carry out a comparison between ‘magic’ and size quantum dots. In doing so, we explore the disadvantages of the size dots. The geometrically optimized coordinates of the bare CdnSen QDs (‘n’ = 6, 12, 13, and 33) have been calculated. The visualization of the cluster is provided in Table 4.1. The geometry optimization leads to a surface reconstruction of the large bare quantum dots, while the core würtzite structure is maintained. As compared with the values for the other three sizes of QDs,
Distance of N-Se (Å) BE of (kcal/mol) H-L Gap (eV) Cd-Se (intra(c)/intra(s)/inter(c)/inter(s)) Cd13Se13 Bare 2.778/2.693/3.102/2.801 -- -- -- 3.06 Cys 2.764/2.705/3.050/2.822 2.908 3.78 -11.157 3.27 MPA 2.773/2.699/3.034/2.843 2.885 -- -11.763 3.26 HSCH(NH2)COOH 2.755/2.702/3.046/2.845 2.856 3.67 -14.446 3.28 HSCH2COOH 2.765/2.700/3.046/2.840 2.885 -- -11.999 3.25 Cd33Se33 Bare 2.869/2.732/2.730/2.756 -- -- -- 2.52 Cys 2.804/2.763/2.955/2.802 2.874 3.79 -12.179 2.80 MPA 2.800/2.758/2.949/2.814 2.895 -- -9.039 2.79 L L
Table .3. Decomposition of the representative TDDFT excited-states of CdnSen (‘n’ = 6, 13) with four ligands and bare Cd33Se33. A full list of transition states of capped Cd6Se6 is in Table A. 3. System Ligands State Index Energy (eV) Oscillator Strength Composition Cd6Se6 -- 3 2.66 0.0684 97% H-2 (Se 4p) — (Cd 5s, Se 5s) 9 3.15 0.0768 61% H-7 (Se 4p) — Cys 3 2.84 0.0635 84% H-2 (Se 4p) — (Cd 5s, Se4p) 8 3.37 0.1294 55% H-7 (Se 4p) — MPA 3 2.86 0.0673 96% H-2 (Se 4p) — L (Cd 5s, Se 5s) 9 3.38 0.1362 85% H-5 (Se 4p) — L SHCH(NH2)COOH 3 2.89 0.0682 96% H (Se 4p) — L (Cd 5s, Se 5s) 9 3.40 0.1059 69% H-5 (Se 4p) — L SHCH2COOH 3 2.85 0.0649 96% H-2 (Se 4p) — L (Cd 5s, Se 5s)
9 3.38 0.1219 47% H-6 (Se 4p) — L 40% H-7 (Se 4p) — L System Ligands State Index Energy (eV) Oscillator Strength Excited-State Composition -- 3 2.72 0.0637 96% H-2 (Se 4p) — L (Cd 5s, Se 5s) 10 3.02 0.1042 90% H-9 (Se 4p) — L Cys 5 2.90 0.0865 96% H-2 (Se 4p) — L (Cd 5s, Se4p) 10 3.25 0.2272 92% H-9 (Se 4p) — L MPA 5 2.91 0.0846 97% H-2 (Se 4p) — L (Cd 5s, Se 5s) 11 3.26 0.2162 92% H-9 (Se 4p) — L SHCH(NH2)COOH 5 2.90 0.0808 95% H-2 (Se 4p) — L (Cd 5s, Se 5s) 11 3.30 0.2276 92% H-9 (Se 4p) — L 3
SHCH2COOH 5 2.89 0.0852 97% H-2 (Se 4p) — L (Cd 5s, Se 5s) 11 3.28 0.2097 91% H-9 (Se 4p) — L Cd33Se33 -- 1 2.19 0.0276 97% H (Se 4p) — L (Cd 5s, Se 5s) 8 2.46 0.0411 94% H-7 (Se 4p) — L 17 2.67 0.0667 79% H-16 (Se 4p) — L 25 2.79 0.0341 67% H-22 (Se 4p) — L
Cd6Se6 Cd12Se12 Cd13Se13 Cd33Se33 Gap (eV) PBE 3.22 2.08 3.11 2.58 3.14 2.10 3.06 2.52 Binding Energy per CdSe pair (eV) PBE 3.728 3.649 3.938 4.114 B3LYP 3.175 3.107 3.398 3.558
DFT XC Functional BE of Cd-L (kcal/mol) H-L Gap (eV) Cd-Se (intra/intra(L)/inter/inter(L)) Cd13Se13 MPA PBE 2.783/2.717/2.902/2.846 2.773/2.699/3.034/2.843 2.858 2.885 -14.447 -11.763 3.31 3.26 HSCH(NH2) -COOH PBE B3LYP 2.767/2.728/2.921/2.845 2.755/2.702/3.046/2.845 2.795 2.856 -17.920 -14.446 3.37 3.28 HSCH2COOH PBE 2.784/2.724/2.906/2.838 2.765/2.700/3.046/2.840 2.850 2.885 -14.470 -11.999 3.34 3.25 Cd33Se33 Bare PBE B3LYP 2.868/2.738/2.739/2.760 2.869/2.732/2.730/2.756 -- -- -- -- 2.58 2.52 Cys PBE B3LYP 2.814/2.799/2.938/2.766 2.804/2.763/2.955/2.802 2.862 2.874 -17.382 -12.179 2.84 2.80 MPA PBE B3LYP 2.807/2.762/2.940/2.839 2.800/2.758/2.949/2.814 2.878 2.895 -13.262 -9.039 2.85 2.79
System Energy (eV) Oscillator Strength Composition Percentage of Contribution Involved Orbitals Bare Cd6Se6 33% H — L+1 3.82 0.0355 42% H — L+3 (Cd 5s, Se 4p, 5s) 34% H-3 (Se 4p) — L+2 4.12 0.0254 50% H-4 — L+2 20% H-3 — L+3 Cys 2.84 0.0635 84% H-2 — L (Cd 5s, Se4p) 3.37 0.1294 55% H-7 (Se 4p) — L 3.37 0.1241 55% H-8 (Se 4p) — L 3.94 0.0372 33% H-10 (N 2p) — L 24% H-1 (Se 4p) — L+3 (Cd 5s, 4p, Se 4p, 5s) 17% H (Se 4p) — L+2 (Cd 5s, 4p, Se 4p, 5s) 4.09 0.0258 36% H-3 (Se 4p) — L+1 (Cd 5s)
System Energy (eV) Oscillator Strength Excited-State Composition Percentage of Contribution Involved Orbitals Cys 4.09 0.0248 37% H-4 (Se 4p) — L+1 4.24 0.0216 26% H-5 (Se 4p) — L+2 21% H-6 (Se 4p) — L+3 4.30 0.0384 25% H-2 (Se 4p) — L+6 (Cd 4p, Se 4p, 5s) MPA 2.86 0.0673 96% H-2 (Se 4p) — L (Cd 5s, Se 5s) 3.38 0.1362 85% H-5 (Se 4p) — L 3.38 0.1362 85% H-6 (Se 4p) — L 3.99 0.0522 29% H-10 (Se 4p) — L 21% H-1 (Se 4p) — L+2 (Cd 5s, 4p, Se 5s, 4p) 21% H (Se 4p) — L+3 (Cd 5s, 4p, Se 5s, 4p) 4.15 0.0214 41% H-4 (Se 4p) — L+2 41% H-3 (Se 4p) — L+2
System Energy (eV) Oscillator Strength Excited-State Composition Percentage of Contribution Involved Orbitals SHCH(NH2)COOH 2.89 0.0682 96% H (Se 4p) — L (Cd 5s, Se 5s) 3.37 0.0273 64% H-8 (Se 4p) — L 18% H-6 (Se 4p) — L 3.37 0.0274 64% H-9 (Se 4p) — L 18% H-5 (Se 4p) — L 3.40 0.1059 69% H-5 — L 23% H-9 — L 3.40 0.1059 69% H-6 — L 23% H-8 — L 4.08 0.0564 43% H — L+6 (Cd 5s, S 3p, C 2s) 4.15 0.0217 18% H-4 (Se 4p) — L+2 (S 3s 3p, C 2s, 2p) 18% H-3 (Se 4p) — L+3 (S 3s 3p, C 2s, 2p)
System Energy (eV) Oscillator Strength Excited-State Composition Percentage of Contribution Involved Orbitals SHCH(NH2)COOH 4.21 0.0205 41% H-5 — L+1 (Cd 5s, S 3s 3p, C 2s, 2p) 4.21 0.0205 41% H-6 — L+1 SHCH2COOH 2.85 0.0649 96% H-2 (Se 4p) — L (Cd 5s, Se 5s) 3.38 0.1219 47% H-6 (Se 4p) — L 40% H-7 (Se 4p) — L 3.38 0.1219 47% H-5 (Se 4p) — L 40% H-8 (Se 4p) — L 3.98 0.047 29% H-10 (Se 4p) — L 19% H-1 (Se 4p) — L+2 (Cd 5s, 4p, Se 5s, 4p) 19% H (Se 4p) — L+3 (Cd 5s, 4p, Se 5s, 4p) 4.10 0.0234 41% H-4 (Se 4p) — L+2 41% H-3 (Se 4p) — L+3
System Energy (eV) Oscillator Strength Excited-State Composition Percentage of Contribution Involved Orbitals SHCH2COOH 4.15 0.0366 26% H-3 — L+1 (Cd 5s, Se 5s, 4p) 25% H-4 — L+3 24% H-3 — L+2 4.15 0.0366 26% H-4 — L+1 24% H-4 — L+2 24% H-3 — L+3 4.34 0.0254 31% H-6 (Se 4p) — L+1 18% H-2 — L+4 (Cd 5s, 4p, Se 5s, 4p) 4.34 0.0254 31% H-5 (Se 4p) — L+1 18% H-2 — L+5 (Cd 5s, 4p, Se 5s, 4p) 4.44 0.0259 59% H-12 (Se 4p) — L