Department of Chemistry and Chemical Sciences, Central University of Jammu, Rahya-Suchani (Bagla), Dist: Samba Jammu-181143, India.
Institute of Chemistry, The Hebrew University, Jerusalem 91904, Israel.
J Chem Theory Comput. 2020 Nov 10;16(11):7005-7016. doi: 10.1021/acs.jctc.0c00725. Epub 2020 Oct 14.
A dual electronic basis set approach is introduced for more efficient but accurate calculations of the anharmonic vibrational spectra in the framework of the vibrational self-consistent field (VSCF) theory. In this approach, an accurate basis set is used to compute the vibrational spectra at the harmonic level. The results are used to scale the potential surface from a more modest but much more efficient basis set. The scaling is such that at the harmonic level the new, scaled potential agrees with one of the accurate basis sets. The approach is tested in the application of the microsolvated, protected amino acid Ac-Phe-OMe, using the scaled anharmonic hybrid potential in the VSCF and VSCF-PT2 algorithms. The hybrid potential method yields results that are in good accord with the experiment and very close to those obtained in calculations with the high-level, very costly potential from the large basis set. At the same time, the hybrid potential calculations are considerably less expensive. The results of the hybrid calculations are much more accurate than those computed from the potential surface corresponding to the modest basis set. The results are very encouraging for using the hybrid potential method for inexpensive yet sufficiently accurate anharmonic calculations for the spectra of large biomolecules.
本文提出了一种双电子基组方法，用于在振动自洽场（VSCF）理论框架内更有效地计算非谐振动光谱，但又能保持较高的准确性。在该方法中，使用精确的基组来计算谐振动水平的振动光谱。然后，用这些结果来缩放来自更为适度但效率更高的基组的势能面。这种缩放的方式是使得在谐振动水平下，新的缩放势能与精确基组之一一致。本文通过应用于微溶剂化、保护的氨基酸 Ac-Phe-OMe，测试了该方法，在 VSCF 和 VSCF-PT2 算法中使用了缩放后的非谐混合势能。混合势能方法得到的结果与实验非常吻合，与使用高成本、大基组的高精度势能计算得到的结果非常接近。同时，混合势能计算的成本要低得多。与对应于适度基组的势能表面计算的结果相比，混合计算的结果要精确得多。这些结果非常令人鼓舞，为使用混合势能方法进行大型生物分子光谱的廉价但足够精确的非谐计算提供了可能。
