[中文文摘]使用分子图形软件设计出多种CnP2+(n=1～7)的结构模型,并进行B3LYP密度泛函几何构型优化和振动频率计算.通过总能量的比较,最稳定的构型是具有D∞h对称性的线性结构.当n为奇数时团簇具有类似的聚炔结构性质,而n为偶数的团簇具有类似的累积二烯烃结构性质.电离能曲线具有明显地奇偶变化的规律,说明了n为奇数的团簇分子比n为偶数团簇稳定,这与激光质谱图的奇强偶弱的实验结果相符合.[英文文摘]Using molecular graphics software,numerous models of C_nP_2+ (n=1~7) have been designed.Geometry optimization and calculation on vibrational frequency were carried out by means of the B3LYP density functional method.After comparing the total energies of the isomers,it was found that the ground state structures were linear chain with D_∞h symmetry with phosphorus atoms located at the terminals.From the bond order analysis by NBO,when n is even (i.e.,in the cases of C_2P_2+,C_4P_2+,C_6P_2+),the straight chains
show an alternate long2and2short pattern in bond lengths that is similar to that of polyacetylene st ructure. When n is
odd (i. e. ,in the cases of C3 P2+ ,C5 P2
+ ,C7 P2+ ) ,the bond lengths of C2C bonds with in the st raight chain average out and are similar to those of the cumulenic structure. The clusters with odd2n are more stable than those with even2n. The odd/ even alternation trend can be explained according to the obvious parity variation of ionization potential ,it is in good agreement with the experimental phenomena observed in mass spectrometric studies.国家自然科学基金资助项目(20473061
