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利用量子化学计算研究了五氟吡啶分子的激发态非绝热弛豫路径中一些关键点的分子结构和能量. 计算确定了五氟吡啶分子基态及两个最低激发态的结构和相应电子态的垂直和绝热激发能, 其中基态是具有C 2v对称性的平面结构, 而激发态结构为平面外畸变的半船型结构. 同时确定了3个锥形交叉S 2/S 1, S 1/S 0, S 2/S 0的拓扑结构和能量. 在分支空间中, 锥形交叉S 2/S 1, S 1/S 0, S 2/S 0的结构都是尖峰不对称结构, 分别为船型、半船型和椅式结构, 其能量分别为6.39, 5.16和8.51 eV. 计算结果表明五氟吡啶分子的非辐射弛豫主要是S 2态上的波包经锥形交叉S 2/S 1快速内转换到S 1态, 再通过S 1/S 0弛豫到基态的路径, 而直接通过S 2/S 0衰减到基态的概率较小.In this work, the molecular structure and energy of some critical points in nonradiative relaxation process of the excited state of pentafluoropyridine are studied through quantum chemistry calculation. The structures and the vertical excitation energies and adiabatic excitation energies of the ground state and two lowest exited states are calculated. The geometry of the ground state is a planar structure with C 2vsymmetry, while the geometries of the two lowest excited states are half-boat structures with out-of-plane distortions. Furthermore, the topology structures and energy of the conical intersections of S 2/S 1, S 1/S 0and S 2/S 0are determined. The topology structures of the conical intersections S 2/S 1, S 1/S 0and S 2/S 0in the branching space are all peaked with asymmetric structures, and are determined to be structure of boat, half-boat, and chair, respectively. Their corresponding energy values are estimated at 6.39, 5.16 and 8.51 eV, respectively. The results show that the primary non-adiabatic relaxation pathway is the wavepacket of the S 2state rapidly evolving into the S 1state via the S 2/S 1, and then directly relaxing to the ground state via the S 1/S 0. In addition, the probability of directly relaxing to the ground state through S 2/S 0is smaller.
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结构参数 S1 S2 B3LYP/
6-311G*M062X/
6-311G*SA-CASSCF/
6-311G*B3LYP/
6-311G*M062X/
6-311G*SA-CASSCF/
6-311G*C1—F1 1.32 1.31 1.31 1.34 1.31 1.29 C2—F2 1.34 1.33 1.33 1.34 1.33 1.33 C3—F3 1.41 1.37 1.37 1.39 1.37 1.29 C4—F4 1.34 1.33 1.33 1.34 1.33 1.32 C5—F5 1.32 1.31 1.31 1.34 1.31 1.30 C1—N 1.32 1.32 1.32 1.33 1.32 1.44 C5—N 1.32 1.32 1.32 1.33 1.32 1.36 C1—C2 1.43 1.43 1.43 1.38 1.43 1.35 C2—C3 1.40 1.40 1.40 1.44 1.40 1.43 C3—C4 1.40 1.40 1.40 1.44 1.40 1.47 C4—C5 1.43 1.43 1.43 1.38 1.43 1.34 C1—C5 2.20 2.18 2.21 2.29 2.18 2.36 C2—C4 2.28 2.28 2.36 2.45 2.28 2.52 N—C1—C2—C5 3.83 5.31 1.13 3.07 5.42 20.69 C3—C2—C1—C4 13.26 13.33 0.30 16.25 13.16 20.64 F3—C3—C4—C1 54.38 52.09 45.11 75.49 51.89 55.04 F4—C4—C5—C1 13.68 14.05 3.13 12.19 14.58 32.02 F5—C5—C4—C2 6.96 9.10 2.96 7.32 9.66 18.20 Methods S1 S2 VEEs Dev/% AEEs Dev/% VEEs AEEs Exp.a) 4.88 — 4.60 — — — RI-SCS-CC2a) 5.10 4.5 4.60 0 6.35 — XMCQDPT2a) 4.89 0.2 4.41 4.1 6.23 5.26 B3LYP 5.33 9.2 4.41 4.1 6.28 5.26 SA-CASSCF(8, 8) 5.47 12.1 4.84 5.2 6.92 6.69 M062X 5.63 9.8 4.80 4.3 6.50 6.15b) CASPT2 5.02 2.9 4.41 4.1 6.33 — 注:a)来自参考文献[22];b)基于M062X/6-31G*的结果 参数 S2/S1 S1/S0 S2/S0 C1—F1 1.30 1.30 1.31 C2—F2 1.32 1.31 1.30 C3—F3 1.30 1.32 1.32 C4—F4 1.32 1.31 1.30 C5—F5 1.30 1.30 1.31 C1—N 1.45 1.31 1.48 C5—N 1.29 1.33 1.42 C1—C2 1.47 1.46 1.49 C2—C3 1.39 1.46 1.48 C3—C4 1.49 1.47 1.47 C4—C5 1.45 1.45 1.49 N—C1—C2—C5 29.72 2.15 22.59 C3—C2—C1—C4 10.90 46.24 12.28 F3—C3—C4—C1 11.57 36.30 64.87 F4—C4—C5—C1 9.84 30.71 0.81 参数 S1/S0 S2/S1 S2/S0 σx/(eV·Å–1) –0.0047 0.1413 0.4016 σy/(eV·Å–1) –0.0207 0.0757 –0.0001 ${\varDelta }_{\mathrm{gh}} $ –0.9904 –0.9796 –0.8647 dgh 1.5000 1.0212 0.6159 -
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