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Quantum and classical studies of calcium and zinc clusters and of pyrrole oligomers.

机译：钙和锌簇以及吡咯低聚物的量子和经典研究。

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An all electron hybrid density functional approach (DFT) with very large basis sets was used for studying Ca2 through Ca19 and Zn3 through Zn11 neutral clusters and their cluster anions. Energetics, structure and vibrational analysis of all these neutral clusters and cluster anions are reported. The calculated electron affinities (EA) are in excellent agreement with experiment. Additionally, the electron detachment binding energies (BE) up to Ca-6 and Zn-6 were identified by analyzing the ground and excited states of the cluster anions and of their corresponding neutral clusters. The theoretical BE is in very good agreement with experiment for both calcium and zinc cluster anions.;Polypyrrole (PPy) is a conjugated polymer prototype of conducting polymers. The energetically preferred spatial conformation and charge distribution of n-Py oligomers (n = 1--24) in both the reduced and oxidized phases are obtained and analyzed in this work within the hybrid density functional theory. Binding energies, HOMO-LUMO gap energies, radius of gyration, end-to-end distance and vibrational frequencies are reported as a function of oligomer length. The band structure of infinite PPy gives a band gap energy in excellent agreement with experiment for reduced PPy. Evolution of the band gap and the charge-localized states as a function of PPy oxidation level is reported.;Based on the DFT results of n-Py oligomers, a classical potential model to treat dense systems of PPy is developed within a modified rigid-ion polarizable force field. This model potential is then used in the Adaptive Tempering Monte Carlo and the Metropolis Monte Carlo simulations of a 192 4-Py system and 64 12-Py system at different densities. The energy, end to end distance, radius of gyration and order parameter as a function of density are inspected. It is shown that these systems have the structural characteristics of liquids. However, the calculations show that as the density is increased, the system develops regions of stacked chains.
机译：使用具有非常大基础集的全电子混合密度泛函方法（DFT）来研究Ca2到Ca19以及Zn3到Zn11中性簇以及它们的簇阴离子。报告了所有这些中性簇和簇阴离子的能量，结构和振动分析。计算的电子亲和力（EA）与实验非常吻合。此外，通过分析簇状阴离子及其对应的中性簇的基态和激发态，可以确定直至Ca-6和Zn-6的电子离解结合能（BE）。理论上的BE与钙和锌簇阴离子的实验非常吻合。聚吡咯（PPy）是导电聚合物的共轭聚合物原型。在混合密度泛函理论中，在这项工作中获得并分析了还原相和氧化相中n-Py低聚物（n = 1--24）在能量上优选的空间构象和电荷分布。据报道，结合能，HOMO-LUMO间隙能，回转半径，端对端距离和振动频率是低聚物长度的函数。无限量PPy的能带结构与减少PPy的实验非常一致地给出了带隙能量。报道了带隙和电荷局部状态随PPy氧化水平的变化。离子极化力场。然后将该模型电势用于不同密度的192 4-Py系统和64 12-Py系统的自适应回火蒙特卡洛和Metropolis蒙特卡洛仿真中。检查能量，端到端距离，回转半径和阶次参数与密度的关系。结果表明，这些系统具有液体的结构特征。但是，计算表明，随着密度的增加，系统会形成堆叠链的区域。

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