Department of Chemistry, University of Copenhagen, Universitetsparken 5, Copenhagen Ø 2100, Denmark.
Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Gothenburg 41296, Sweden.
J Phys Chem A. 2021 Dec 9;125(48):10330-10339. doi: 10.1021/acs.jpca.1c07737. Epub 2021 Nov 22.
Molecular photoswitches can under certain conditions be used to store solar energy in the so-called molecular solar thermal storage systems, which is an interesting technology for renewable energy solutions. The current investigations focus on the performance of seven different density functional theory (DFT) methods (B3LYP, CAM-B3LYP, PBE0, M06-2X, ωB97X-D, B2PLYP, and PBE0DH) when predicting geometries and thermochemical properties of the [2.2.2]-bicyclooctadiene (BOD) photoswitch. We find that all of the investigated DFT methods provide geometries that are in good agreement with those obtained using coupled cluster singles and doubles (CCSD) calculations. The dependence on the employed basis set is not large when predicting geometries. With respect to the thermochemical properties, we find that the M06-2X, CAM-B3LYP, PBE0, and ωB97X-D functionals all predict thermochemical properties that are in good agreement with the results of the CCSD, the CCSD including perturbative triples (CCSD(T)), and the explicitly correlated CCSD-F12 and CCSD(T)-F12 models. Lastly, for energy calculations, we tested the newly developed fourth-order cluster perturbation theory singles and doubles CPS(D-4) model, which in this study provides energy differences that are of CCSD and sometimes also CCSD(T) quality at a relatively low cost. We find that the CPS(D-4) model is an excellent choice for further investigation of BOD derivatives because accurate energies can be obtained routinely using this methodology. From the results, we also note that the predicted storage energies and storage energy densities for the BOD photoswitch are very large compared to other molecular solar thermal storage systems and that these systems could be candidates for such applications.
分子光开关在某些条件下可以用于在所谓的分子太阳能热存储系统中存储太阳能，这是可再生能源解决方案的一项有趣技术。目前的研究重点是七种不同密度泛函理论（DFT）方法（B3LYP、CAM-B3LYP、PBE0、M06-2X、ωB97X-D、B2PLYP 和 PBE0DH）在预测[2.2.2]-二环辛二烯（BOD）光开关的几何形状和热化学性质时的性能。我们发现，所有研究的 DFT 方法提供的几何形状都与使用耦合簇单双（CCSD）计算得到的几何形状非常吻合。在预测几何形状时，所使用的基组的依赖性不大。关于热化学性质，我们发现 M06-2X、CAM-B3LYP、PBE0 和 ωB97X-D 泛函都预测了与 CCSD、包括微扰三（CCSD(T)）和显式相关 CCSD-F12 和 CCSD(T)-F12 模型的结果非常吻合的热化学性质。最后，对于能量计算，我们测试了新开发的四阶集群微扰理论单双激发 CPS(D-4)模型，在本研究中，该模型以相对较低的成本提供了与 CCSD 有时甚至 CCSD(T)质量相当的能量差异。我们发现，CPS(D-4)模型是进一步研究 BOD 衍生物的绝佳选择，因为可以使用这种方法常规获得准确的能量。从结果中，我们还注意到 BOD 光开关的存储能量和存储能量密度与其他分子太阳能热存储系统相比非常大，并且这些系统可能是此类应用的候选者。
