TTF^(+1)-π共轭桥-6-氧四联氮阳离子双自由基NLO性质的理论研究

Theoretical Study on NLO Properties of TTF^(+1)-π Conjugated Bridge-verdazyl Cation Diradicals

采用量子化学UPBE1PBE结合有限场(FF)方法,对系列TTF+?-π共轭桥-6-氧四联氮阳离子双自由基体系的稳定性,极化率αs和第一超极化率βtot进行研究.结果表明,TTF+?-6-氧四联氮阳离子双自由基引入共轭桥后,随体系共轭性增强,αs和βtot值均增大(体系2S的βtot值除外).自旋多重度和构象对双自由基体系的极化率和第一超极化率都有影响,双自由基体系由单重态转变为三重态时,极化率减小,而第一超极化率明显增大.以体系2为例,在单重态时αs和βtot值随构象变化较小,而三重态时αs和βtot值随二面角θ1和θ2的增加而减小.

The stabilities,polarizabilities α s and the first hyperpolarizabilities β tot for a series of TTF＋？-π conjugated bridge-verdazyl cation diradicals were investigated by using the UPBE1PBE method combined with the finite field（FF） approach.The results indicate that introducing conjugated bridges to TTF＋？-verdazyl cation diradicals results in the conjugation of systems increasing,and then the α s and β tot values increasing（except for the β tot value of system 2S）.The spin multiplicity and conformation both have in-fluence on polarizability and the first hyperpolarizability.The polarizabilities of all systems decrease when the diradical systems change from singlet into triplet,while the first hyperpolarizabilities increase obviously.Taking the system 2 for example,the α s and β tot values change slightly with conformation in singlet,while the α s and β tot values decrease with increasing of the dihedral angle θ1 and θ2 in triplet.