RT3: A Windows program for the Renner–Teller analysis of Π 2 states of triatomic molecules

Abstract In this work we present Windows and Fortran programs which can be used for the Renner-Teller analysis of the vibronic levels of ^2 Π states of linear, triatomic molecules. The programs can do least squares fitting of term values relative to the lowest energy level within a single ^2 Π state, of combination differences between vibronic levels within a single ^2 Π state or of transitions between the levels of two different ^2 Π states. The algorithm allows for the inclusion of Renner-Teller, sp... Title of program: RT3 Catalogue Id: AEAL_v1_0 Nature of problem The vibronic levels of triatomic molecules in 2 π states are complicated by spin-orbit and vibrational-orbital angular momentum coupling (Renner-Teller) effects that make them difficult to assign and analyze. The RT3 program, available in Windows and Fortran versions, can be used to calculate the vibronic energy levels of such systems and fit experimental data to a Hamiltonian that includes Renner-Teller, spin-orbit, vibrational anharmonicity, Fermi resonance and Sears resonance effects. Versions of this program held in the CPC repository in Mendeley Data AEAL_v1_0; RT3; 10.1016/j.cpc.2007.11.017 This program has been imported from the CPC Program Library held at Queen's University Belfast (1969-2019)**摘要** 本研究提出可用于线型三原子分子²Π电子态振电子能级雷纳-泰勒（Renner-Teller）分析的Windows与Fortran程序。该程序可针对以下三类对象执行最小二乘拟合：单一²Π电子态内相对于最低能级的项值、单一²Π电子态内各振电子能级间的组合差值，以及两种不同²Π电子态能级间的跃迁。本算法支持纳入雷纳-泰勒、sp...效应。 程序名称：RT3 目录编号：AEAL_v1_0 问题本质：三原子分子在²Π电子态下的振电子能级会受到自旋-轨道耦合与振动-轨道角动量耦合（雷纳-泰勒（Renner-Teller）效应）的干扰，导致能级归属与分析难度显著提升。RT3程序提供Windows与Fortran两个版本，可用于计算此类体系的振电子能级，并将实验数据拟合至包含雷纳-泰勒、自旋-轨道、振动非谐性、费米共振（Fermi resonance）以及西尔斯共振（Sears resonance）效应的哈密顿量中。 存放在Mendeley Data中的CPC知识库的程序版本：AEAL_v1_0; RT3; 10.1016/j.cpc.2007.11.017。 本程序源自贝尔法斯特女王大学馆藏的CPC程序库（1969-2019）。