Mladenović Mirjana, Botschwina Peter, Puzzarini Cristina
Institut für Physikalische Chemie, Universität Göttingen, Tammannstrasse 6, D-37077 Göttingen, Germany.
J Phys Chem A. 2006 Apr 27;110(16):5520-9. doi: 10.1021/jp056743u.
We report large-scale quantum mechanical calculations for the HCCN radical in its ground electronic state. A six-dimensional potential energy surface based on MR-ACPF/cc-pVQZ ab initio energy points is developed and adjusted to reproduce experimental findings for and nu1 of HCCN. Rovibrational energy levels of HCCN and DCCN are computed for total rotational angular momentum J = 0-4 by making use of combined (functional + point wise) coordinate representations together with contraction schemes resulting from several diagonalization/truncation steps. The classical barrier to linearity is determined to be 287 cm(-1). Spectroscopic parameters are calculated for low lying states and compared with available experimental data. Energy patterns attributed to the nu4 bending mode and to the quasilinear nu5 bending mode are identified. It has been also found that nu2 and nu3 + (nu4(1),nu5(1))(0,0) are coupled in HCCN, while the mixing between nu3 and (2nu4(0), 2nu5(0))(0,0) is seen in DCCN.
我们报告了处于基电子态的HCCN自由基的大规模量子力学计算。基于MR - ACPF/cc - pVQZ从头算能量点构建并调整了一个六维势能面，以重现HCCN的 和ν1的实验结果。利用组合（泛函 + 逐点）坐标表示以及由几个对角化/截断步骤产生的收缩方案，计算了总转动角动量J = 0 - 4时HCCN和DCCN的振转能级。确定线性化的经典势垒为287 cm⁻¹。计算了低能态的光谱参数，并与现有实验数据进行比较。识别出了归因于ν4弯曲模式和准线性ν5弯曲模式的能量模式。还发现HCCN中ν2和ν3 + (ν4(1),ν5(1))(0,0)耦合，而在DCCN中观察到ν3和(2ν4(0), 2ν5(0))(0,0)之间的混合。
