This post is about a little trick I have for speeding up my quantum chemistry calculations. For some reason this software is unknown to most people, and thus I decided do a short advertisement!
The bottleneck in all forms of computational quantum chemistry is the CPU time spent to converge a calculation to a given accuracy. The most expensive part is in most cases the evaluation of two-electron integrals, but during many calculations, a lot of time is also spent doing linear algebra operations. The computational routines for doing linear algebra has been optimized greatly over the years and today there are quite a few standard linear algebra libraries for doing this. One standard API of linear algebra routines is called BLAS, short for "Basic Linear Algebra Subprograms". Many equations involved in quantum chemistry are formulated into matrix notation which is easily interpreted and turned into fast, parallelized code.
When people want to use a fast BLAS library, often well-known libraries such as the ALTAS or Intel MKL BLAS libraries are used. However, there is a slightly faster BLAS library out there, named GotoBLAS2. This library was started by a Japanese guy named Kazushige Goto (the Japanese pronunciation is something lik "go-toe"), who, like Albert Einstein, worked in a patent office while he began developing his own BLAS library. After a while he was 'discovered' by a university in Texas and soon Goto was deported from Japan. Now he is said to be very rich and working for some large coporation somewhere in the US.
Enough with the history! Tobias Wittwer has made a detailed comparison of common, fast BLAS libraries in this pdf: blas_lapack.pdf
You can download the latest GotoBLAS2 here. Not only is GotoBLAS2 faster than Intel's MKL library, GotoBLAS2 is also completely free of charge and open source under the BSD license.
GotoBLAS2 will be used in future posts on compiling and installing software, for which I am always using GotoBLAS2. So be sure to use this and make the most of your CPU resources!