Our new article “Fast evaluation of two-center integrals over Gaussian charge distributions and Gaussian orbitals with general interaction kernels” (J. Chem. Theory Comput. 2020, https://doi.org/10.1021/acs.jctc.9b01296)
has just been published. \o/

The article describes a simple and efficient method of computing general interactions over charge clouds expanded over spherical Gaussian functions (of arbitrary angular momenta), which we expect to be particularly useful for semi-empirical quantum chemistry methods (but also for high angular momenta in conventional and F12 quantum chemistry). To make it accessible to a broad audience, the article and its supporting information are comprehensive and contain large amounts of background information and derivations on integration methods for general cases, and on how to construct and use kernel functions for general two-particle interactions.

It also includes a do-as-you-like-licensed open source C++ implementation of the Boys function in its supporting information, including generators, and a full algorithm description in the SI appendix G.

In the software section, ir-wmme v20200228 has been released, which includes the algorithms described in the article.

-cgk

Check out the recently published paper on The Density Fitting J + X Approximation in which we use the auxiliary density expansion introduced by Laikov and the Laplacian of the electron density as described by Perdew and Constatin in LL-TPSS as well as Yu, He, and Truhlar in MN15-L. Here we efficiently use these mGGA functionals with only a 10-20% increase in computational cost compared to GGA functionals.

-avb

https://pubs.acs.org/doi/abs/10.1021/acs.jctc.7b01083

One of the boons of starting a new research group is that you get to set up a group homepage. With colors and pictures \o/. Only… how do you do it? Traditional raw HTML and CSS? Or blog style? I decided to give WordPress a try, not the least because it is already set up by the nice people at ITS at Penn State. Yes, I am a blogger now! We will see how it goes. Until this page is populated, I would also like to point to http://www.theochem.uni-stuttgart.de/~knizia/, which still contains information not moved yet—including the source code to various software I developed over the years. Over time things will hopefully become available here, once I find more time and… figure out how to upload files.

Isn’t it great how technology simplifies everything? 8)

– cgk