An efficient method for computing the QTAIM topology of a scalar field: The electron density case

An efficient method for computing the quantum theory of atoms in molecules (QTAIM) topology of the electron density (or other scalar field) is presented. A modified Newton-Raphson algorithm was implemented for finding the critical points (CP) of the electron density. Bond paths were constructed with the second-order Runge-Kutta method. Vectorization of the present algorithm makes it to scale linearly with the system size. The parallel efficiency decreases with the number of processors (from 70% to 50%) with an average of 54%. The accuracy and performance of the method are demonstrated by computing the QTAIM topology of the electron density of a series of representative molecules. Our results show that our algorithm might allow to apply QTAIM analysis to large systems (carbon nanotubes, polymers, fullerenes) considered unreachable until now. © 2012 Wiley Periodicals, Inc. The Bader's quantum theory of atoms in molecules (QTAIM) was used in a wide range of applications from solid state physics and X-ray crystallography to drug design and biochemistry. However, it has not always been feasible to apply QTAIM to large systems due to its computational cost. This article presents a vectorized and parallel algorithm for computing the QTAIM topology of the electron density that scales linearly with the system size and quasi-linearly with the number of processors. The method is applied to a series of representative molecules.