The potential energy surface (PES) of a molecular system constitutes a cornerstone for every theoretical study of spectroscopy and dynamics. We introduce here AUTOSURF, our general code for the automated construction of PESs. The presented version is designed for van der Waals (vdW) systems composed of two (rigid) fragments. The fitting algorithms are based on the local interpolating moving least squares methodology, and have many advanced features such as options for data-point placement, iterative refinement based on various criteria, and symmetry recognition. The code interfaces to popular electronic structure codes such as MOLPRO and CFOUR to automatically generate ab initio PESs for 3D (atom - general molecule) and 4D (linear molecule - linear molecule) vdW systems. The niche of these algorithms is for treating highly anisotropic interactions which are challenging for traditional quadrature type expansions. The method is well suited to producing negligible (arbitrarily small) fitting error for cases with subtle topological features and multiple wells. We will show examples of PESs with fitting errors below 1 cm−1, and even below 0.01 cm-1, constructed using between a few hundred and a few thousand ab initio points.

AUTOSURF: A code for automated construction of potential energy surfaces

256th National Meeting (2018)

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