小水的可靠结构和电子能量使用密度功能和局部相关性合集群模型化学
Benjamin T Petty1, Vance R Fowler1, Audrey Ryu1
1Department of Chemistry, Furman University, Greenville, South Carolina 29613, United States.
The journal of physical chemistry. A
|September 25, 2025
概括
基于域的局部对自然轨道合集群单双和三倍 (DLPNO-CCSD(T)) 方法准确地预测水集群的相对能量. 使用DLPNO-CCSD或MP2方法的优化结构与DLPNO-CCSD单点能量提供了一个快速而精确的方法.
科学领域:
- 计算化学的计算化学
- 量子化学 是一个量子化学.
- 理论化学 理论化学
背景情况:
- 精确计算水群的相对能量对于理解它们的特性至关重要.
- 高级计算方法,如合集群单双和三倍 (CCSD(T)) 在计算上昂贵.
- 基于域的局部对自然轨道合集群单双和三重 (DLPNO-CCSD) 提供了一个更有效的替代方案.
研究的目的:
- 评估DLPNO-CCSD方法在复制水群的基准相对能量的准确性 ((H2O) n=3-7).
- 调查不同几何优化方法对相对能量的精度的影响.
- 确定计算效率高的协议,用于精确计算水集群的能量.
主要方法:
- 使用CCSD:T:MP2程序优化了基准的几何形状.
- 基准相对能量是使用明确相关的CCSD (T) -F12b单点能量 (SPE) 来计算的.
- DLPNO-CCSD ((T) 计算是用各种基础集进行的,包括对完整基础集 (CBS) 极限进行推算.
- 评估了要求较低的几何优化方法 (ωB97X-D DFT 和密度合适的MP2).
主要成果:
- 具有三次ζ或更大的基准集的DLPNO-CCSD(T) 与基准CCSD(T) -F12数据 (MAD ≤0.13 kcal/mol) 显示出极好的一致性.
- 从 ωB97X-D/6-31++G (d,p) 和密度调整的MP2/haTZ进行优化结构,在使用DLPNO-CCSD (T) SPEs时,产生了与基准数据非常接近的相对能量.
- 在DLPNO-CCSD(T) SPEs的基础集中包含分散函数显著影响了能量精度.
结论:
- DLPNO-CCSD ((T) 方法是计算水群相对能量的一种可靠而准确的方法.
- 优化结构的B97X-D/6-31++G(d,p) 和增强基础集的DLPNO-CCSD(T) SPEs的组合提供了一个快速而准确的协议.
- 这种优化的协议可以有效和精确地确定水集群异构体的相对电子能量.
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