DOI: 10.5061/dryad.j3tx95xc3
title: Molecular dynamics trajectories for ionic conductors in: Paradigms of frustration in superionic solid electrolytes

description: Superionic solid electrolytes have widespread use in energy devices, but
 the fundamental motivations for fast ion conduction are often elusive.
 Here, we draw upon atomistic simulations of a wide range of halide, oxide,
 sulfide, and closo-borate superionic conductors to illustrate some of the
 key features that enhance local cation mobility in these solids. We
 classify three types of frustration that create competition between
 different local atomic preferences, thereby flattening the diffusive
 energy landscape and enhancing entropy. These include chemical
 frustration, which derives from competing factors in the anion-cation
 interaction; structural frustration, which is connected to the lack of a
 clear site preference for mobile ion ordering; and dynamical frustration,
 which is associated with temporary fluctuations in the energy landscape
 due to anion orientations or cation reconfigurations. For each class of
 frustration, we provide detailed simulation analyses of multiple materials
 to show how ion mobility is facilitated, resulting in stabilizing factors
 that are both entropic and enthalpic in origin. Implications for
 identifying suitable descriptors for superionic conductivity are
 discussed.
description: Ab initio molecular dynamics trajectories (xyz format, zipped)
 collected on Livermore Computing facilities and on the Stampede2 system at
 the University of Texas, Austin. All simulations used
 Perdew-Burke-Ernzerhof (PBE) pseudopotentials with Gamma-only k-point
 sampling in the NVT ensemble. AgI, CuI,
 Li<sub>2</sub>B<sub>12</sub>H<sub>12</sub>, Li<sub>2</sub>B<sub>10</sub>H<sub>10</sub>, Na<sub>2</sub>B<sub>10</sub>H<sub>10</sub>, Li<sub>10</sub>GeP<sub>2</sub>S<sub>12</sub>: Trajectories are from Car-Parrinello molecular dynamics simulations using the CP module within Quantum Espresso using ultrasoft pseudopotentials from the Quantum Espresso standard pseudopotential library. Nose-Hoover chains were used to maintain temperature.   Li<sub>3</sub>PS<sub>4</sub>: Trajectories are from Born-Oppenheimer molecular dynamics simulations using the Vienna Ab-initio Simulation Package (VASP) and projector augmented wave pseudopotentials. A Nose-Hoover thermostat was used to maintain temperature. 
description: Li<sub>3</sub>PS<sub>4</sub>: 50 ps, 700
 K, 128 atoms, lattice parameters <em>a</em> = 12.78
 Å, <em>b</em> = 15.74 Å, <em>c</em> = 12.04 Å,
 time step = 1.0 fs, output every frame. AgI (alpha
 phase): 34.5 ps, 700 K, 108 atoms, lattice parameter
 <em>a</em> = 15.46 Å, electronic mass = 400 a.u., time step =
 0.29 fs, output every 10 frames (2.9 fs). CuI (alpha
 phase): 37 ps, 700 K, 108 atoms, lattice parameter <em>a</em>
 = 14.34 Å, electronic mass = 800 a.u., time step = 0.19 fs, output every
 10 frames (1.9 fs).
 Li<sub>2</sub>B<sub>12</sub>H<sub>12</sub> (beta phase, fcc): 51 ps, 800 K, sqrt(2) x sqrt(2) x 1 supercell, lattice parameters <em>a </em>= 14.21 Å, <em>c </em>= 10.05 Å, electronic mass = 400 a.u., time step = 0.145 fs, output every 10 frames (1.45 fs). Li<sub>2</sub>B<sub>10</sub>H<sub>10</sub> (fcc): 55 ps, 800 K, sqrt(2) x sqrt(2) x 1 supercell, lattice parameters <em>a </em>= 14.51 Å, <em>c </em>= 10.26 Å, electronic mass = 400 a.u., time step = 0.145 fs, output every 10 frames (1.45 fs). Na<sub>2</sub>B<sub>10</sub>H<sub>10</sub> (fcc): 60 ps, 800 K, sqrt(2) x sqrt(2) x 1 supercell, lattice parameters <em>a </em>= 13.96 Å, <em>c </em>= 9.87 Å, electronic mass = 400 a.u., time step = 0.145 fs, output every 10 frames (1.45 fs). Li<sub>10</sub>GeP<sub>2</sub>S<sub>12</sub>: 47 ps, 700 K, sqrt(2) x sqrt(2) x 1 supercell, lattice parameters <em>a </em>= 12.69 Å, <i>c</i> = 12.45 Å, electronic mass = 400 a.u., time step = 0.145 fs, output every 10 frames (1.45 fs).