星际尘埃HC_(3-x)NC_x(x=0～3)与HC_(5-x)NC_x(x=0～5)分子的DFT研究

Study of Interstellar Medium HC_ (3-x )NC_x (x=0～3) and HC_ 5-x NC_x (x=0～5) by Density Functional Theory

运用密度泛函理论 (DFT)中的B3LYP方法 ,计算了星际尘埃HC3 N ,HC5N分子及它们的同分异构体的分子结构、相对稳定性、偶极矩、转动常数等 .对于HC3 -xNCx(x =0～ 3) ,HC3 N分子比其它的异构体要稳定 .将计算所得的HC3 N ,HC2 NC的转动常数B0 与实际的观测值B0 相比较 ,发现两者能较好地吻合 .比较HC5-xNCx(x =0～ 5 )的各同分异构体的总能量 ,发现HC5N的相对稳定性最高 ,但它的偶极矩相对较低 .将HC5N的转动常数B0 的理论计算值与实际观测值进行比较 ,其相对标准误差仅 0 .6 % .

The molecular structures, relative stabilities, dipole moments and rotational constants of HC 3N, HC 5N and their isomers are calculated by B3LYP/6 311++G ** . In HC 3- x NC x ( x =0～3), HC 3N is found to be the most stable structure. The rotational constants B 0 values of HC 3N and HC 2NC which are obtained from B3LYP/6 311++G ** are almost exactly in accordance with the experimental values. In HC 5- x NC x ( x =0～5), HC 5N is found to be more stable than other isomers, but its dipole moment is relatively small. For the rotational constants B 0 of HC 5N, the relative standard deviation between the calculated value and the experimental value is only 0.6%.