Adam Ahmad Y, Yachmenev Andrey, Yurchenko Sergei N, Jensen Per
Fakultät Mathematik und Naturwissenschaften, Physikalische und Theoretische Chemie, Bergische Universität Wuppertal, D-42097 Wuppertal, Germany.
Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom.
J Chem Phys. 2015 Dec 28;143(24):244306. doi: 10.1063/1.4938253.
We present the first variational calculation of the isotropic hyperfine coupling constant of the carbon-13 atom in the CH3 radical for temperatures T = 0, 96, and 300 K. It is based on a newly calculated high level ab initio potential energy surface and hyperfine coupling constant surface of CH3 in the ground electronic state. The ro-vibrational energy levels, expectation values for the coupling constant, and its temperature dependence were calculated variationally by using the methods implemented in the computer program TROVE. Vibrational energies and vibrational and temperature effects for coupling constant are found to be in very good agreement with the available experimental data. We found, in agreement with previous studies, that the vibrational effects constitute about 44% of the constant's equilibrium value, originating mainly from the large amplitude out-of-plane bending motion and that the temperature effects play a minor role.
我们给出了在温度T = 0、96和300 K下，对CH₃自由基中碳 - 13原子的各向同性超精细耦合常数的首次变分计算。它基于新计算的基态CH₃的高水平从头算势能面和超精细耦合常数面。通过使用计算机程序TROVE中实现的方法，变分计算了转动 - 振动能级、耦合常数的期望值及其温度依赖性。发现耦合常数的振动能量以及振动和温度效应与现有实验数据非常吻合。与先前的研究一致，我们发现振动效应约占该常数平衡值的44%，主要源于大幅度的面外弯曲运动，而温度效应起次要作用。
