Accurate Potential Energy Surfaces Using Atom-Centered Potentials and Minimal High-Level Data

We demonstrate that a Δ-density functional theory
(Δ-DFT)
approach based on atom-centered potentials (ACPs) represents a computationally
inexpensive and accurate method for representing potential energy
surfaces (PESs) for the HONO and HFCO molecules and vibrational frequencies
derived therefrom. Using as few as 100 CCSD(T)-F12a reference energies,
ACPs developed for use with B3LYP/def2-TZVPP are shown to produce
PESs for HONO and HFCO with mean absolute errors of 27.7 and 5.8
cm–1, respectively. Application of the multiconfigurational
time-dependent Hartree (MCTDH) method with ACP-corrected B3LYP/def2-TZVPP
PESs produces vibrational frequencies for cis- and trans-HONO with mean absolute percent errors (MAPEs) of
0.8 and 1.1, compared to 0.8 obtained for the two isomers with CCSD(T)-F12a/cc-pVTZ-F12/MCTDH.
For HFCO, the vibrational frequencies obtained using the present (Δ-DFT)/MCTDH
approach give a MAPE of 0.1, which is the error obtained with CCSD(T)-F12a/cc-pVTZ-F12/MCTDH.
The ACP approach is therefore successful in representing a PES calculated
at a high level of theory (CCSD(T)-F12a) and a promising method for
the development of a general protocol for the representation of accurate
molecular PESs and the calculation of molecular properties from them.