...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Beyond the Potential Energy Surface: Ab initio Corrections to the Born-Oppenheimer Approximation for H_2O
【24h】

Beyond the Potential Energy Surface: Ab initio Corrections to the Born-Oppenheimer Approximation for H_2O

机译：超越势能面：H_2O的Born-Oppenheimer近似从头算修正

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

It is customary when computing ro-vibrational transitions in molecules to invoke the Born-Oppenheimer separation between nuclear and electronic motion. However, it is known from accurate calculations on H_2~+ and H_2 that the first-order (diagonal adiabatic) and second-order (nonadiabatic) corrections are not negligible and are both important. In the present work, we have made an ab initio implementation of the Bunker and Moss formalism for the nonadiabatic correction and applied it to H_2 and H_2O. From comparison to accurate calculations for H_2, we find that we can obtain good results for the nonadiabatic correction using CI singles to treat the electronically excited states if we scale the results, but we must go beyond the SCF approximation to obtain an accurate diagonal adiabatic correction. For H_2O, we find that the first-order correction is more important than the second-order correction for bending energy levels, but the second-order correction is more important than the first-order correction for stretching energy levels. The correction to rotational levels is also significant. Thus, first- and second-order corrections are vital for accurate ab initio predictions of transition frequencies.
机译：计算分子中的旋转振动跃迁以调用核运动和电子运动之间的Born-Oppenheimer分离时，这是惯例。但是，从对H_2〜+和H_2的精确计算中可以知道，一阶（对角绝热）和二阶（非绝热）校正不可忽略，并且都很重要。在当前的工作中，我们从头开始实现了Bunker和Moss形式主义以进行非绝热校正，并将其应用于H_2和H_2O。通过对H_2的比较和精确计算，我们发现，如果对结果进行缩放，则可以使用CI单值处理电子激发态来获得非绝热校正的良好结果，但是我们必须超越SCF逼近才能获得准确的对角绝热校正。对于H_2O，我们发现对于弯曲能级，一阶校正比二阶校正更重要，但是对于拉伸能级，二阶校正比一阶校正更重要。旋转水平的校正也很重要。因此，一阶和二阶校正对于准确的从头算起过渡频率的预测至关重要。

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