对于明确相关的MP2的自动区分
Erica C Mitchell1,2, Justin M Turney2, Henry F Schaefer1,2
1Department of Chemistry, University of Georgia, 302 East Campus Road, Athens, Georgia 30602, United States.
自动分化 (AD) 现在计算了MP2-F12等复杂波函数方法的导数,以前缺乏分析梯度. 这一进步使强大的量子化学模型能够进行新的计算,包括红外强度.
科学领域:
- 量子化学 是一个量子化学.
- 计算化学计算化学
- 理论化学 理论化学
背景情况:
- 自动分化 (AD) 允许计算波函数方法的任意顺序导数.
- AD一直局限于具有现有的分析梯度或响应理论的方法.
- 显式相关的MP2 (MP2-F12) 是一个强大的近似,缺乏可用的导数.
研究的目的:
- 将AD应用于MP2-F12/3C(FIX) +CABS方法,该方法缺乏可用的衍生工具.
- 通过将它们与有限差异计算进行比较来验证AD结果.
- 为了实现新的预测,例如IR强度,使用AD对MP2-F12.
主要方法:
- 对于MP2-F12/3C(FIX) +CABS方法的AD的实施.
- 用AD计算优化几何,双极时刻和Hessian与有限差异结果的比较.
- 计算和分析MP2-F12 / 3C ((FIX) +CABS振动频率和红外强度.
主要成果:
- 来自AD的优化几何与有限差异匹配到~10^-3 Å (债券长度) 和~10^-6° (角度).
- 通过AD计算的双极时刻与有限的差异一致,为~10^-6 D.
- 黑森协议显示了轻微的差异 (~10^-5),归因于当前的AD实施限制.
- 振动频率在~10^-2cm^-1.的范围内显示出极好的一致性.
- 第一次预测MP2-F12/3C(FIX) +CABS IR强度使用AD.
结论:
- AD已成功应用于MP2-F12/3C(FIX) +CABS,将其实用性扩展到没有先前分析衍生品的方法.
- AD提供了精确的几何和二极点,并有可能改进赫森计算.
- 计算红外强度的能力为理论光谱学开辟了新的途径,具有明确相关的方法.
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