Reducing the Cost of Using Collocation to Compute Vibrational Energy Levels: Results for CH2NH
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Authors
Avila, Gustavo
Carrington, Tucker Jr
Date
2017-07-31
Type
journal article
Language
en
Keyword
Vibrational Energy Transfer , Collocation Methods , Chemical Compounds , Eigenvalues , Group Theory
Alternative Title
Abstract
In this paper, we improve the collocation method for computing vibrational spectra that was presented in the work of Avila and Carrington, Jr. [J. Chem. Phys. 143, 214108 (2015)]. Known quadrature and collocation methods using a Smolyak grid require storing intermediate vectors with more elements than points on the Smolyak grid. This is due to the fact that grid labels are constrained among themselves and basis labels are constrained among themselves. We show that by using the so-called hierarchical basis functions, one can significantly reduce the memory required. In this paper, the intermediate vectors have only as many elements as the Smolyak grid. The ideas are tested by computing energy levels of CH2NH.