{"title":"Symmetry-Adapted Models for the Hyperpolarizability of Water.","authors":"Ryan Elwood-Clarke, David Wilkins","doi":"10.1088/1361-648X/adbfec","DOIUrl":null,"url":null,"abstract":"<p><p>Accurately modelling nonlinear optical experiments such as second-harmonic scattering and hyper-Raman scattering requires the hyperpolarizability $\\boldsymbol{\\beta}$, a nonlinear dielectric response to an applied electric field. The hyperpolarizability tensor is a computationally expensive quantity to calculate, making it a natural target for machine-learning methods. We test a family of recently developed models for the hyperpolarizability of water, trained on small clusters containing up to 8 water molecules. These models are able to predict $\\boldsymbol{\\beta}$ for larger clusters, with more complex structures than those observed in the training set. For configurations of bulk water, the agreement is not so straightforward: while the total hyperpolarizability is quite well described, the predicted \\textit{molecular} $\\boldsymbol{\\beta}$ tensors vary wildly between models. This means that while experiments whose outputs depend on total hyperpolarizability can be accurately modelled, those that require molecular quantities will require improved models.</p>","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":" ","pages":""},"PeriodicalIF":2.3000,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Physics: Condensed Matter","FirstCategoryId":"101","ListUrlMain":"https://doi.org/10.1088/1361-648X/adbfec","RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"PHYSICS, CONDENSED MATTER","Score":null,"Total":0}
引用次数: 0
Abstract
Accurately modelling nonlinear optical experiments such as second-harmonic scattering and hyper-Raman scattering requires the hyperpolarizability $\boldsymbol{\beta}$, a nonlinear dielectric response to an applied electric field. The hyperpolarizability tensor is a computationally expensive quantity to calculate, making it a natural target for machine-learning methods. We test a family of recently developed models for the hyperpolarizability of water, trained on small clusters containing up to 8 water molecules. These models are able to predict $\boldsymbol{\beta}$ for larger clusters, with more complex structures than those observed in the training set. For configurations of bulk water, the agreement is not so straightforward: while the total hyperpolarizability is quite well described, the predicted \textit{molecular} $\boldsymbol{\beta}$ tensors vary wildly between models. This means that while experiments whose outputs depend on total hyperpolarizability can be accurately modelled, those that require molecular quantities will require improved models.
期刊介绍:
Journal of Physics: Condensed Matter covers the whole of condensed matter physics including soft condensed matter and nanostructures. Papers may report experimental, theoretical and simulation studies. Note that papers must contain fundamental condensed matter science: papers reporting methods of materials preparation or properties of materials without novel condensed matter content will not be accepted.