We present the parametrization and benchmark of long-range corrected second-order density functional tight binding (DFTB), LC-DFTB2, for organic and biological molecules. The LC-DFTB2 model not only improves fundamental orbital energy gaps but also ameliorates the DFT self-interaction error and overpolarization problem, and further improves charge-transfer excited states significantly. Electronic parameters for the construction of the DFTB2 Hamiltonian as well as repulsive potentials were optimized for molecules containing C, H, N, and O chemical elements. We use a semiautomatic parametrization scheme based on a genetic algorithm. With the new parameters, LC-DFTB2 describes geometries and vibrational frequencies of organic molecules similarly well as third-order DFTB3/3OB, the de facto standard parametrization based on a GGA functional. LC-DFTB2 performs well also for atomization and reaction energies, however, slightly less satisfactorily than DFTB3/3OB.

中文翻译：

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远程校正的有机分子DFTB2的参数化和基准测试

我们介绍了有机和生物分子的远程校正的二阶密度功能紧密结合（DFTB）LC-DFTB2的参数化和基准。LC-DFTB2模型不仅改善了基本轨道能隙，而且改善了DFT自相互作用误差和超极化问题，并进一步显着改善了电荷转移激发态。对于包含C，H，N和O化学元素的分子，优化了用于构造DFTB2哈密顿量的电子参数以及排斥势。我们使用基于遗传算法的半自动参数化方案。利用新参数，LC-DFTB2可以类似地描述有机分子的几何形状和振动频率，以及三阶DFTB3 / 3OB （事实上​​是基于GGA功能的标准参数化。LC-DFTB2在雾化和反应能方面也表现出色，但是，其令人满意的程度比DFTB3 / 3OB稍差。