...
  • 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 >The Arsenic Fluorides AsF_n (n = 1-6) and Their Anions: Structures, Thermochemistry and Electron Affinities
【24h】

The Arsenic Fluorides AsF_n (n = 1-6) and Their Anions: Structures, Thermochemistry and Electron Affinities

机译：氟化砷AsF_n（n = 1-6）及其阴离子：结构，热化学和电子亲和力

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 molecular structures, electron affinities, and dissociation energies of the AsF_n/AsF_n~- (n = 1-6) species have been examined using four hybrid and pure density functional theory (DFT) methods. The basis set used in this work is of double-ζ plus polarization quality with additional diffuse s- and p-type functions, denoted DZP++. The geometries are fully optimized with each DFT method independently. Three types of energy separations reported in this work are the adiabatic electron affinity (EA_ad), the vertical electron affinity (EA_vert), and the vertical detechment energy (VDE). The first As-F dissociation energies D_e(F_(n-1)As-F) for AsF_n, and both D_e(F_(n-1)As~--F) and D_e(F_(n-1)As-F~-) species have also been reported. The best method for predicting molecular structures was found to be BHLYP, while other methods generally overestimated bond lengths. For the closed-shell anions the As-F bond distances are ～0.1 A longer than those for the analogous neutrals. In contrast, when the neutral AsF_n is a closed shell, the anion As-F distances is ～0.2 A longer. The most reliable adiabatic electron affinities, obtained at the DZP++BHLYP level of theory, are 0.74 eV (As), 0.94 eV (AsF), 1.17 eV (AsF_2), 0.80 eV (AsF_3), 4.42 eV (AsF_4), and 2.79 eV (AsF_5), respectively. Those for As and AsF_2 are in good agreement with experiment, but that for AsF is smaller than the available experimental value (1.3 ± 0.1 eV). The predicted vertical detachment energy for AsF_6~- is remarkable, as large as 10.54 eV (BHLYP), indicating AsF_6~- is stable. The general trend for predicting the first dissociation energies is BP86 ～ BLYP > B3LYP BHLYP. The first dissociation energies for the neutral arsenic fluorides predicted by the DFT methods except BHLYP are 4.22-4.5 eV (AsF), 4.45-4.74 eV (AsF_2), 4.76-5.03 eV (AsF_3) 1.46-1.84 eV (AsF_4), and 3.87-4.11 eV (AsF_5). Compared to the experimental dissociation energies, the theoretical predictions are very reasonable. The anion bond dissociation energies are largely unknown experimentally. The dissociation energy for AsF~- → As + F~- is predicted to be 1.73 eV (BHLYP), 1.82 eV (B3LYP), 1.93 eV (BP86), and 1.87 eV (BLYP), which values are in good agreement with experiment (1.92 ± 0.2 eV). The predicted bond dissociation energies for D_e(F_3As-F~-) are in the range of 2.45-2.57 eV, which is close to the previous theoretical results using the HF and MP2/ECP methods. For the vibrational frequencies of the AsF_n series, the BHLYP method also produces good predictions with the average error only about 10 cm~(-1) from available experimental values. The other three methods underestimate the vibrational frequencies, with the worst predictions given by the BLYP method.
机译：使用四种混合和纯密度泛函理论（DFT）方法研究了AsF_n / AsF_n〜-（n = 1-6）物种的分子结构，电子亲和力和解离能。在这项工作中使用的基础集是双ζ加上极化质量以及附加的扩散S和P型函数，表示为DZP ++。每种DFT方法都对几何形状进行了完全优化。这项工作中报告的三种能量分离类型是绝热电子亲和力（EA_ad），垂直电子亲和力（EA_vert）和垂直分解能量（VDE）。 AsF_n的第一个As-F解离能D_e（F_（n-1）As-F）以及D_e（F_（n-1）As〜-F）和D_e（F_（n-1）As-F 〜-）种也有报道。发现预测分子结构的最佳方法是BHLYP，而其他方法通常会高估键长。对于闭壳阴离子，As-F键距比类似中性离子的键距长约0.1A。相反，当中性AsF_n为封闭壳时，阴离子As-F的距离要长〜0.2A。在DZP ++ BHLYP理论水平上获得的最可靠的绝热电子亲和力为0.74 eV（As），0.94 eV（AsF），1.17 eV（AsF_2），0.80 eV（AsF_3），4.42 eV（AsF_4）和分别为2.79 eV（AsF_5）。 As和AsF_2的那些与实验非常吻合，但是AsF的那些小于可用的实验值（1.3±0.1 eV）。 AsF_6〜-的预测垂直脱离能非常显着，高达10.54 eV（BHLYP），表明AsF_6〜-是稳定的。预测第一离解能的一般趋势是BP86〜BLYP> B3LYP BHLYP。用DFT方法预测的除BHLYP以外的中性氟化砷的第一离解能为4.22-4.5 eV（AsF），4.45-4.74 eV（AsF_2），4.76-5.03 eV（AsF_3）1.46-1.84 eV（AsF_4）和3.87 -4.11 eV（AsF_5）。与实验离解能相比，理论预测是非常合理的。阴离子键解离能在很大程度上是实验未知的。 AsF〜-→As + F〜-的离解能预计为1.73 eV（BHLYP），1.82 eV（B3LYP），1.93 eV（BP86）和1.87 eV（BLYP），这些值与实验吻合良好（1.92±0.2 eV）。 D_e（F_3As-F〜-）的预测键解离能在2.45-2.57 eV的范围内，这与使用HF和MP2 / ECP方法的先前理论结果相近。对于AsF_n系列的振动频率，BHLYP方法也产生了良好的预测，与可用的实验值相比平均误差仅为10 cm〜（-1）。其他三种方法低估了振动频率，而BLYP方法给出的预测最差。

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