Fragment Molecular Orbital Based Parametrization Procedure for Mesoscopic Structure Prediction of Polymeric Materials

Abstract

In the analyses of miscibility behaviors of macromolecules and polymers, dissipative particle dynamics (DPD) simulations are generally performed. In these simulations, the so-called χ parameters describing the effective interactions among particles are crucial. It has been known that such parameters can be obtained within the classical or empirical force field frameworks. However, there is a potential problem that charge transfer and polarization occasionally occur. Additionally, satisfactory reference parameters are not available for some cases. Therefore, we developed a new procedure to evaluate the set of parameters by using the ab initio fragment molecular orbital (FMO) method which can provide the set of interaction energies among segments as polymer units. Moreover, we evaluated the anisotropy of molecules by using the FMO-based effective interaction parameters for three standard binary mixture systems (hexane-nitrobenzene, polyisobutylene-diisobutyl ketone, and polyisoprene-polystyrene). The calculated values showed good agreement with the experimental values with about 10% errors.

Theoretical analyses on water cluster structures in polymer electrolyte membrane by using dissipative particle dynamics simulations with fragment molecular orbital based effective parameters

“…Fan et al proposed the procedure to calculate Z and DE 12 , based on MC simulations with classical FF set. 72 Recently, we have developed a new procedure 76,77 to estimate the c parameter set through a series of FMO calculations, 80,81 where the electronic effects of polarization and charge transfer were incorporated in the energy evaluation and also the molecular anisotropy was taken into account. Consequently, the c parameter could be calculated using the following equation…”

“…Recently, we have developed a new procedure 76,77 to estimate the χ parameter set through a series of FMO calculations, 80,81 where the electronic effects of polarization and charge transfer were incorporated in the energy evaluation and also the molecular anisotropy was taken into account. Consequently, the χ parameter could be calculated using the following equation where Z ij is the coordination number of segment j around segment i , and S ij corresponds to the scaling factor associating with anisotropy (refer to ref.…”

“…75 Although ab initio evaluations of c parameters for DPD are desirable, its applicability could be limited due to the enlarged computational costs when the molecular sizes of segment pairs grows. Therefore, we have developed a new approach 76,77 to calculate such effective parameters based on the fragment molecular orbital (FMO) method. [78][79][80][81][82] This procedure could be considered as an extension of Fan's method 72 based on the Flory-Huggins theory.…”

“…The crucial interaction parameters among DPD particles were evaluated through our new protocol with FMO. 76,77 Furthermore, the network connectivity of water clusters was evaluated through the percolation analysis of formed water clusters in PEM, 15,58,[85][86][87][88] since such an effective index should relate with the conductivity. Naon and SPEEK were compared.…”

<b>A portable code for dissipative particle dynamics (DPD) simulations with additional specific interactions</b>

“…The structures of -helix and -sheet were successfully formed for protein models through the inclusion of additional potentials [13]. Recently, a non-empirical way to evaluate effective interaction parameters for DPD simulations has been developed by us [37], based on the fragment molecular orbital (FMO) calculations [38]. This new parameterization protocol would be applicable even to amino acid residues as the components of proteins, since such biochemical molecules could be quantitatively treated by the FMO method in a straightforward fashion.…”