Barone Vincenzo, Carnimeo Ivan, Scalmani Giovanni
Scuola Normale Superiore, Piazza dei Cavalieri 7, 56126, Pisa, Italy.
INFN Sezione di Pisa, Edificio C - Polo Fibonacci Largo B. Pontecorvo, 3-56127 Pisa, Italy.
J Chem Theory Comput. 2013 Apr 9;9(4):2052-71. doi: 10.1021/ct301050x. Epub 2013 Mar 18.
The Density Functional Tight Binding (DFTB) and Time Dependent DFTB (TD-DFTB) methods have been coupled with the Polarizable Continuum Model (PCM) of solvation, aiming to study spectroscopic properties for large systems in condensed phases. The calculation of the ground and the excited state energies, together with the analytical gradient and Hessian of the ground state energy, have been implemented in a fully analytical and computationally effective approach. After sketching the theoretical background of both DFTB and PCM, we describe the details of both the formalism and the implementation. We report a number of examples ranging from vibrational to electronic spectroscopy, and we identify the strengths and the limitations of the DFTB/PCM method. We also evaluate DFTB as a component in a hybrid approach, together with a more refined quantum mechanical (QM) method and PCM, for the specific case of anharmonic vibrational spectra.
密度泛函紧束缚（DFTB）方法和含时密度泛函紧束缚（TD-DFTB）方法已与可极化连续介质溶剂化模型（PCM）相结合，旨在研究凝聚相中大型体系的光谱性质。基态和激发态能量的计算，以及基态能量的解析梯度和海森矩阵，已通过一种完全解析且计算高效的方法得以实现。在概述了DFTB和PCM的理论背景之后，我们描述了形式体系和实现方法的细节。我们报告了一系列从振动光谱到电子光谱的示例，并确定了DFTB/PCM方法的优点和局限性。我们还针对非谐振动光谱的具体情况，评估了DFTB作为混合方法中的一个组件与更精确的量子力学（QM）方法及PCM一起使用时的情况。
