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首页> 外文期刊>The Journal of Chemical Physics >Density-functional errors in ionization potential with increasing system size
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Density-functional errors in ionization potential with increasing system size

机译:随着系统尺寸的增大,电离势的密度函数误差

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This work investigates the effects of molecular size on the accuracy of density-functional ionization potentials for a set of 28 hydrocarbons, including series of alkanes, alkenes, and oligoacenes. As the system size increases, delocalization error introduces a systematic underestimation of the ionization potential, which is rationalized by considering the fractional-charge behavior of the electronic energies. The computation of the ionization potential with many density-functional approximations is not size-extensive due to excessive delocalization of the incipient positive charge. While inclusion of exact exchange reduces the observed errors, system-specific tuning of long-range corrected functionals does not generally improve accuracy. These results emphasize that good performance of a functional for small molecules is not necessarily transferable to larger systems. (C) 2015 AIP Publishing LLC.
机译:这项工作研究了分子大小对28种碳氢化合物(包括一系列烷烃,烯烃和低聚苯乙炔)的密度函数电离势精度的影响。随着系统尺寸的增加,离域误差会导致系统地低估电离电势,可通过考虑电子能量的分数电荷行为将其合理化。由于初始正电荷的过度离域,具有许多密度泛函近似值的电离电势的计算在尺寸上不大。虽然包括精确交换可以减少观察到的错误,但针对远程校正功能的系统特定调整通常不会提高准确性。这些结果强调,小分子官能团的良好性能不一定能转移到较大的系统。 (C)2015 AIP Publishing LLC。

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