MP2还不够好：用于精确VPT2频率的迁移学习ML模型
MP2 Is Not Good Enough: Transfer Learning ML Models for Accurate VPT2 Frequencies
摘要：
在足够高水平的量子化学理论下，计算小到中等尺寸分子的非谐模式以将实验测量的频率分配给相应类型的分子运动在计算上是具有挑战性的。在这里，一个实用的和负担得起的方法来计算耦合集群质量非谐频率使用二阶振动微扰理论（VPT 2）从机器学习模型。该方法被称为“NN + VPT 2”，使用高维神经网络（PhysNet）来学习不同理论水平的势能面（PES），从中可以有效地确定谐波和VPT 2频率。NN + VPT 2方法应用于8种小至中等大小的分子（H $_2$ CO、trans-HONO、HCOOH、CH $_3$ OH、CH $_3$ CHO、CH $_3$ NO $_2$、CH $_3$ COOH和CH $_3$ CONH $_2$），并在MP 2/aug-cc-pVTZ、CCSD（T）/aug-cc-pVTZ和CCSD（T）-F12/aug-cc-pVTZ-F12理论水平下从NN学习模型报告频率。对于最大的分子和最高水平的理论，迁移学习（TL）用于确定必要的全维，近平衡PES。总体而言，NN + VPT 2产生的非谐波频率在实验确定的频率的20 cm $^{-1}$内，对于接近90%的可用最高质量PES模式，并且对于超过60%的模式，在10 cm $^{-1}$内。对于MP2 PES，仅约60%的NN + VPT 2频率在实验的20 cm $^{-1}$内，与实验相比，离群值高达150 cm $^{-1}$。它也表明，该方法允许提供正确的分配强相互作用的模式，如OH弯曲和OH扭转模式在甲酸单体和CO-拉伸和OH-弯曲模式在乙酸。
英文摘要：
The calculation of the anharmonic modes of small to medium sized molecules for assigning experimentally measured frequencies to the corresponding type of molecular motions is computationally challenging at sufficiently high levels of quantum chemical theory. Here, a practical and affordable way to calculate coupled-cluster quality anharmonic frequencies using second order vibrational perturbation theory (VPT2) from machine-learned models is presented. The approach, referred to as "NN + VPT2", uses a high-dimensional neural network (PhysNet) to learn potential energy surfaces (PESs) at different levels of theory from which harmonic and VPT2 frequencies can be efficiently determined. The NN + VPT2 approach is applied to eight small to medium sized molecules (H$_2$CO, trans-HONO, HCOOH, CH$_3$OH, CH$_3$CHO, CH$_3$NO$_2$, CH$_3$COOH and CH$_3$CONH$_2$) and frequencies are reported from NN-learned models at the MP2/aug-cc-pVTZ, CCSD(T)/aug-cc-pVTZ and CCSD(T)-F12/aug-cc-pVTZ-F12 levels of theory. For the largest molecules and at the highest levels of theory, transfer learning (TL) is used to determine the necessary full-dimensional, near-equilibrium PESs. Overall, NN + VPT2 yields anharmonic frequencies to within 20 cm$^{-1}$ of experimentally determined frequencies for close to 90 % of the modes for the highest quality PES available and to within 10 cm$^{-1}$ for more than 60 % of the modes. For the MP2 PESs only around 60 % of the NN + VPT2 frequencies were within 20~cm$^{-1}$ of the experiment, with outliers up to 150 cm$^{-1}$ compared with experiment. It is also demonstrated that the approach allows to provide correct assignments for strongly interacting modes such as the OH bending and the OH torsional modes in formic acid monomer and the CO-stretch and OH-bend mode in acetic acid.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
