• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>The Journal of Chemical Physics >Toward accurate thermochemistry of the (MgH)-Mg-24, (MgH)-Mg-25, and (MgH)-Mg-26 molecules at elevated temperatures: Corrections due to unbound states
【24h】

Toward accurate thermochemistry of the (MgH)-Mg-24, (MgH)-Mg-25, and (MgH)-Mg-26 molecules at elevated temperatures: Corrections due to unbound states

机译：在高温下实现（MgH）-Mg-24，（MgH）-Mg-25和（MgH）-Mg-26分子的精确热化学：由于未结合态而引起的校正

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The total partition functions Q (T) and their first two moments Q' (T) and Q '' (T), together with the isobaric heat capacities C-p (T), are computed a priori for three major MgH isotopologues on the temperature range of T = 100-3000 K using the recent highly accurate potential energy curve, spin-rotation, and non-adiabatic correction functions of Henderson et al. [J. Phys. Chem. A 117, 13373 (2013)]. Nuclear motion computations are carried out on the ground electronic state to determine the (ro) vibrational energy levels and the scattering phase shifts. The effect of resonance states is found to be significant above about 1000 K and it increases with temperature. Even very short-lived states, due to their relatively large number, have significant contributions to Q (T) at elevated temperatures. The contribution of scattering states is around one fourth of that of resonance states but opposite in sign. Uncertainty estimates are given for the possible error sources, suggesting that all computed thermochemical properties have an accuracy better than 0.005% up to 1200 K. Between 1200 and 2500 K, the uncertainties can rise to around 0.1%, while between 2500 K and 3000 K, a further increase to 0.5% might be observed for Q '' (T) and Cp (T), principally due to the neglect of excited electronic states. The accurate thermochemical data determined are presented in the supplementary material for the three isotopologues of (MgH)-Mg-24, (MgH)-Mg-25, and (MgH)-Mg-26 at 1 K increments. These data, which differ significantly from older standard data, should prove useful for astronomical models incorporating thermodynamic properties of these species. (C) 2015 AIP Publishing LLC.
机译：对于温度范围内的三个主要MgH同位素，先验计算了总分配函数Q（T）及其前两个矩Q'（T）和Q''（T），以及等压热容Cp（T）。使用Henderson等人的最新高度精确的势能曲线，自旋旋转和非绝热校正函数计算T = 100-3000K。 [J.物理化学A 117，13373（2013）]。在基态电子状态下进行核运动计算，以确定（ro）振动能级和散射相移。发现共振态的影响在约1000 K以上会很明显，并且会随着温度的升高而增加。由于数量相对较多，即使寿命很短的状态，在高温下对Q（T）也会有很大的贡献。散射状态的贡献约为共振状态的四分之一，但符号相反。给出了可能的误差源的不确定性估计，这表明所有计算出的热化学性质在1200 K以下时的精度都优于0.005％。在1200至2500 K之间，不确定度可以上升到0.1％左右，而在2500 K至3000 K之间，观察到的Q''（T）和Cp（T）进一步增加到0.5％，这主要是由于忽略了激发电子态。所确定的准确热化学数据在补充材料中以（KgH）-Mg-24，（MgH）-Mg-25和（MgH）-Mg-26的三种同位素形式提供，增量为1 K.这些数据与以前的标准数据有很大不同，应该证明对结合了这些物种热力学性质的天文模型很有用。 （C）2015 AIP Publishing LLC。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号