Accurate parameterization of the kinetic energy functional for calculations using exact-exchange
| Autor: | Babak Sadigh, John E. Klepeis, Brian Gallagher, Vasily V. Bulatov, Phanish Suryanarayana, Shashikant Kumar, Sebastien Hamel, Siya Zhu, Amit Samanta |
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| Rok vydání: | 2022 |
| Předmět: | |
| Zdroj: | The Journal of Chemical Physics. 156:024107 |
| ISSN: | 1089-7690 0021-9606 |
| Popis: | Our ability to perform large scale electronic structures calculations is severely limited by the algorithmic difficulties associated with a Kohn-Sham density functional theory (KSDFT) calculation and the absence of accurate density- dependent kinetic energy functionals required for orbital-free density functional theory calculations (OFDFT). There- fore, the development of accurate density-dependent kinetic energy functionals is important for OFDFT calculations of large realistic systems. To this end, we propose a method to train kinetic energy functional models at the exact-exchange level of theory by using a dictionary of physically relevant terms that have been proposed in the literature in conjunction with linear or non-linear regression methods to obtain the fitting coefficients. For our dictionary, we use gradient expansion of the kinetic energy, non-local models proposed in the literature and their nonlinear combinations, such as a model that incorporates spatial correlations between higher order derivatives of electron density at two points. The predictive capabilities of these models are assessed by using a variety of model one-dimensional systems that exhibit diverse bonding characteristics, such as a chain of eight hydrogens, LiF, LiH, C4H2, C4N2 and C3O2. We show that by using data from KSDFT calculations performed using the exact-exchange functional for only a few neutral structures, it is possible to generate models with high accuracy for charged structures as well as structures obtained from a self- consistent field iteration. In addition, we show that it possible to learn both the orbital dependent terms, i.e., the kinetic energy and the exact-exchange energy. |
| Databáze: | OpenAIRE |
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