线型碳链HC2nB（n=1～10）的电子光谱的理论研究

Electronic Spectra of Linear Carbon Chains HC2nB （n = 1-10）

应用密度泛函理论（DFT），在B3LYP／6—31G^＊＊水平上优化得到了线型簇合物HCznB（n=1～10）的基态平衡几何构型，并计算了它们的谐振动频率．在基态平衡构型下，通过EOM-CCSD／cc-pvDZ的计算，确定了簇合物HC2nB（n=1～5）的X^1∑^＋→1^1∑^＋电子跃迁的垂直激发能；结果表明，体系HC2nBX^1∑^＋1^1∑^＋电子跃迁能与体系大小”之间都存在非线性关系，并导出了它们与”之间的解析表达式．用CASSCF／6—31G^＊方法优化得到了HC2nB（n=1～4）的基态和激发态的平衡几何构型，由于两者成键性质的不同，从而导致了体系的跃迁能与体系大小之间的非线性关系．

Using density functional theory （DFT）, the geometries and the vibrational frequencies of the ground states for linear chains HC2n B （n = 1-10） have been investigated at the B3LYP/6-31G^＊＊ level. Under the optimized ground state geometry, EOM-CCSD/cc-pvDZ has been used to calculate the vertical transition energies for the X^1∑^＋ →1^1∑^＋ transition in HC2, B（n= 1-5）. On the basis of present calculations, the explicit nonlinear expressions for the size dependence of the excitation energy in linear carbon chains HC2, B have been suggested. CASSCF/6-31G^＊ method has been used to locate both the ground and excited states for HC2nB（n=1-4）. Different bonding leads to nonlinear relationship between the excitation energy and n.