The polarizability（α） and second hyperpolarizability（γ） were systemically investigated for singlet diradical complex involving X（X=B,Al,Ga） atom.The results show that both the α and γ can be effectively tuned by varying the distance R（between compound A and a water molecule） and acceptor atom X.The lone pair of electrons from the O atom of the water molecule entered into the vacant p orbital of atom X,which increased the diradical character and led to the increase of the α and γ values.Furthermore,the polarizable continuum model（PCM） was used to test the effects of H2O and CCl4 solvents on the α and γ values.Both the α and γ values of the studied diradical complex 1a（1b,1c） in H2O and CCl4 were uniformly enhanced.And the solvent effects of H2O on either α or γ were larger than those of CCl4.
LIU Hai-boQIU Yong-qingYANG Guo-chunLIU Chun-guangSUN Shi-ling
The polarizabilities and hyperpolarizabilities of the tetrahydropyrrole diradical in different electronic states have been investigated using ab initio and density functional theory （DFT） methods combined with the finite field （FF） approach. The polarizability average value as is a maximum for the singlet state, while that for the closed-shell is a minimum. The trend in second hyperpolarizability average value yis in good agreement with that for as The yvalues of the singlet and triplet states are, respectively, about 3 and 2 times larger than that of the closed-shell. The order of the first hyperpolarizability total effective value βtot is βot （closed shell） βtot （singlet） 〉 βtot （triplet）. The as, βtot, and 7 values of different electronic states obtained using the B3LYP and MP4SDQ methods are close to those obtained using the reliable CCSD method. The nonlinear optical （NLO） properties of two systems isoelectronic with the tetrahydropyrrole diradical-cyclopentane and tetrahydrofuran diradicalsshow that the polarizabilities and hyperpolarizabilities of these systems are all smaller than those of the tetrahydropyrrole diradical in the three electronic states.
SUN XiaoNaQIU YongQingSUN ShiLingLIU ChunGuangDU YanQingSU ZhongMin
