ct8b00603_si_013.xlsx (37.14 kB)
Development of Polarizable Gaussian Model for Molecular Mechanical Calculations I: Atomic Polarizability Parameterization To Reproduce ab Initio Anisotropy
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posted on 2019-01-15, 00:00 authored by Junmei Wang, Piotr Cieplak, Ray Luo, Yong DuanA set of atomic polarizability parameters
for a new polarizable
Gaussian model (pGM) has been developed with the goal to accurately
reproduce the polarizability anisotropy, taking advantage of its ability
to attenuate all short-range electrostatic interactions, by fitting
the ab initio molecular polarizability tensors (Apq) calculated at the B3LYP/aug-cc-pVTZ
level. For comparison, we also rederived the parameters for three
Thole models in which the 1–2 (bonded), 1–3 (separated
by two bonds), and 1–4 (separated by three bonds) interactions
are fully included. The average percent errors (APEs) of molecular
polarizability tensors for 4842 molecules or dimers are 2.98, 3.76,
3.28, and 3.82% for the pGM, Thole linear, Thole exponential, and
Thole Amoeba models, respectively, with atom-type independent, universal
screening factors (USF). The APEs are reduced further to 2.30, 2.69,
2.25, and 2.48% for the four corresponding polarizable models with
atom-type dependent, variable screening factors (VSF). It is encouraging
that the pGM with variable screening factors achieved APEs of 1.83
for 1155 amino acid analogs, dipeptides, and tetrapeptides, 1.39 for
28 nucleic acid bases, 0.708 for 1464 water clusters, and 1.99 for
85 dimers of water and biological building blocks. Compared to the
new set of models, the APEs of the old Thole models that were fitted
to isotropic molecular polarizabilities are 8.7% for set A (without
the 1–2 and 1–3 interactions) and 6.3% for set D (with
the 1–2 and 1–3 interactions) models, respectively.
MPAD, a metric of molecular polarization anisotropy difference based
on the diagonal terms of molecular polarizability tensors was defined
and applied to assess the polarizable models in reproducing the ab initio molecular polarization anisotropy. The MPADs are
3.71, 4.70, 4.11, and 4.77% for the pGM, Thole linear, Thole exponential,
and Thole Amoeba USF models, respectively. The APEs are reduced further
to 2.85, 3.58, 2.90, and 3.15% for the four corresponding VSF models.
Thus, the new pGM and Thole models notably improve molecular polarization
anisotropy. Since pGM attenuates all short-range electrostatic interactions,
its application is expected to improve stability in charge fitting,
energy, and force calculations and the accuracy of multibody polarization.
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polarizability tensorsThole Amoeba modelsscreening factorspolarization anisotropy differenceinteractionAPEAtomic Polarizability Parameterizationpolarizable modelspGMThole Amoeba USF models1464 water clustersReproduce ab Initio AnisotropyThole modelsB 3LYP levelpolarization anisotropyab initioMPADVSFMolecular Mechanical Calculations
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