A new auxiliary basis set for (almost) all the elements of the periodic table optimized for accurate and fast TDDFT calculations

Recently, a new algorithm, polTDDFT, to solve the TDDFT equations for large systems has been proposed and implemented in ADF [1]. PolTDDFT is a valid alternative to the Casida – Davidson approach when a very large number of excitations are needed. This typically is the case for large metal clusters, especially in the plasmonic regime.

The polTDDFT method extracts the absorption spectrum as the imaginary part of the polarizability, solving the TDDFT with respect to the induced density, which is expanded with an auxiliary basis set of STO functions. This auxiliary set must be optimized for the polTDDFT, and up to now it was available only for few elements of the periodic table.

Researchers from the University of Trieste recently developed and published a new set of auxiliary basis function suitable to fit the induced electron density for all elements of the periodic table, except lanthanides and actinides [2]. The basis sets have been optimized in order to furnish accurate absorption spectra using the complex polarizability algorithm of TDDFT. An automatic procedure has been implemented, which evaluates the resemblance of suitable descriptors of the calculated spectra with the auxiliary basis compared to a reference Casida calculation. In this way, it has been possible to reduce the size of the basis sets, while maximizing the basis set accuracy. By employing a collection of molecules for each element, the optimized bases have been shown to be transferable to molecules outside the collection. The final sets are therefore much more accurate and smaller than the previously optimized ones, and have been already included in the database of the last release of the Amsterdam Modeling Suite. The availability of the present new set will drastically improve the applicability range of the polTDDFT method with higher accuracy and less computational effort.

Learn more? Check out Mauro Stener’s webinar in October! See also the polTDDFT section in the ADF manual.

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[1] O. Baseggio, G. Fronzoni, M. Stener, A New Time Dependent Density Functional Algorithm for Large Systems and Plasmons in Metal Clusters, J. Chem. Phys., 143, 024106 (2015).
[2] M. Medves, G. Fronzoni, M. Stener, Optimization of Density Fitting Auxiliary Slater Type Basis Functions for Time Dependent Density Functional Theory, J. Comput. Chem. 43, 1923 (2022).

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