New optimization scheme to obtain interaction potentials for oxide glasses

Abstract

We propose a new scheme to parameterize effective potentials that can be used to simulate atomic systems such as oxide glasses. As input data for the optimization, we use the radial distribution functions of the liquid and the vibrational density of state of the glass, both obtained from ab-initio simulations, as well as experimental data on the pressure dependence of the density of the glass. For the case of silica, we find that this new scheme facilitates finding pair potentials that are significantly more accurate than previous ones even if the functional form is the same, thus demonstrating that even simple two-body potentials can be superior to more complex three-body potentials. We have tested the new potential by calculating the pressure dependence of the elastic moduli and find a good agreement with the corresponding experimental data.

New interaction potentials for borate glasses with mixed network formers

“…In the present work we have used an optimization scheme similar to the one developed earlier 27,28 to include the network former boron into our set of interaction parameters by reproducing the liquid structure at high temperature, and the density, coordination and elastic modulus of the glass at room temperature. Parameters from the previous optimization for silica and aluminosilicates 27,28 were maintained to ensure transferability and a similar charge balancing scheme suggested by Habasaki et al 34 was used to partially emulate the polarization effect.…”

“…In this section, we show how the optimization scheme developed by us in our previous work 28 was adapted to include the network former boron into the set of potentials for glasses with mixed network formers. 6 2 4…”

“…and , { , , , , , , } O Si Li Na K Al B    . All the parameters from our previous work 27,28 were maintained constant and oxygen charge was evaluated for each compositions in order to maintain charge neutrality by using a similar scheme as described previously 27,34 . The short-range interactions were cut off at 8 Å while the Coulombic interactions were cut off at 10 Å.…”

“…The electronic convergence criterion for the residual minimization method-direct inversion in iterative space 40 was fixed at 5×10 −7 eV. These parameters were chosen based on previous studies performed on pure silica glass 28 and sodium borosilicate glasses 46 .…”

“…In our previous work 27 , we used an optimization scheme similar to the one developed for silica 28 and extended the interaction parameter set to include alkali modifiers lithium, sodium and potassium, alkaline earth modifier calcium, and aluminum that can behave as a modifier or a former depending on the composition 29,30 . In this work, we adapt a similar optimization approach to include the network former boron into our parameter set to allow MD simulations of glasses with mixed network formers.…”