A fast hybrid method for constructing multidimensional potential energy surfaces from ab initio calculations: A new global analytic PES of NH2 system

- A hybrid scheme to construct potential energy surfaces (PESs) is proposed.
- The hybrid scheme shows enhanced stability and accuracy.
- The hybrid scheme is shown to be able to construct high quality PESs.
- A new analytic ab initio PES for N(2D) + H2 reactive system is constructed.

A hybrid fitting scheme is proposed for the construction of global analytic ab initio potential energy surfaces (PESs) by means of applying reproducing kernel Hilbert space (RKHS) interpolation and cubic spline interpolation onto different dimensions of the molecular configuration space. In addition to inheriting most advantages of the pure RKHS method, this scheme offers the following extra benefits: short initiation time and enhanced stability and accuracy. We also propose a fast algorithm for the scheme allowing the PES computation time to be independent of the number of ab initio points. We have constructed an adiabatic PES of N(2D) + H2→NH + H reactive system from more than twenty thousand ab initio points using this scheme. The accurate quantum dynamics results calculated on the constructed PES demonstrate high accuracy and efficiency of this new scheme.