Yang2026 Potential¶

The Yang2026 potential is a Buckingham-based force field parameterized for borosilicate glass systems containing Na, Ca, B, and Si. It uses partial charges scaled from formal values and was developed alongside machine-learning-optimized parameters to serve as a transferable classical reference.

Reference¶

K. Yang, R. Chen, A.K.R. Christensen, M. Bauchy, N.M.A. Krishnan, M.M. Smedskjaer, F. Rosner. "Transferable potential for molecular dynamics simulations of borosilicate glasses and structural comparison of machine learning optimized parameters", J. Non-Cryst. Solids 684, 124104 (2026). DOI:10.1016/j.jnoncrysol.2026.124104

Functional Form¶

The pairwise interaction uses the Buckingham form:

\[ V(r_{ij}) = A_{ij} \, e^{-r_{ij}/\rho_{ij}} - \frac{C_{ij}}{r_{ij}^6} + \frac{q_i q_j}{r_{ij}} \]

where:

Symbol	Description
\(A_{ij}\)	Repulsion energy prefactor (eV)
\(\rho_{ij}\)	Repulsion range parameter (Å)
\(C_{ij}\)	Van der Waals attraction coefficient (eV·Å⁶)
\(q_i, q_j\)	Partial atomic charges

For DSF/Wolf electrostatics, LAMMPS does not provide a combined buck/coul/dsf style, so the generator uses hybrid/overlay:

LAMMPS pair style (DSF default): hybrid/overlay coul/dsf 0.182 11.0 buck 11.0

LAMMPS pair style (PPPM/Ewald): buck/coul/long 11.0

Charges¶

All charges are fixed at values scaled by 0.5 from formal charges:

Element	Charge (\(e\))
O	−0.945
Na	+0.4725
Ca	+0.945
B	+1.4175
Si	+1.89

Pair Parameters¶

Parameters from Tables II and III of Yang et al. (2026). Only the interactions listed below are parameterized — unlisted pairs (e.g. Si–Na) carry no short-range interaction and interact only via Coulomb.

Pair	\(A_{ij}\) (eV)	\(\rho_{ij}\) (Å)	\(C_{ij}\) (eV·Å⁶)
O–O	9022.79	0.2650	85.0921
Si–O	50306.10	0.1610	46.2978
B–O	191757.12	0.1249	32.5600
B–B	532.85	0.3527	0.0
Si–B	337.70	0.2900	0.0
Na–O	120303.80	0.1700	0.0
Ca–O	155667.70	0.1780	42.2597

Supported Elements¶

Yang2026 supports 5 elements targeting Na/Ca borosilicate systems:

Element	Role in glass
Si	Network former
B	Network former
Na	Network modifier
Ca	Network modifier
O	Anion

Usage¶

from amorphouspy import get_structure_dict, generate_potential
from amorphouspy import DsfConfig, PppmConfig

structure_dict = get_structure_dict(
    {"SiO2": 70, "B2O3": 15, "Na2O": 10, "CaO": 5},
    target_atoms=3000,
)

# Default: DSF electrostatics
potential = generate_potential(structure_dict, potential_type="yang2026")

# PPPM for periodic long-range accuracy
potential = generate_potential(
    structure_dict,
    potential_type="yang2026",
    electrostatics=PppmConfig(kspace_accuracy=1e-5),
)

Electrostatics options¶

Because LAMMPS has no buck/coul/dsf style, DSF and Wolf use hybrid/overlay. PPPM and Ewald use the native buck/coul/long style.

Config class	Emitted pair style
`DsfConfig` (default)	`hybrid/overlay coul/dsf <alpha> <cutoff> buck <src>`
`WolfConfig`	`hybrid/overlay coul/wolf <alpha> <cutoff> buck <src>`
`PppmConfig`	`buck/coul/long <cutoff>` + `kspace_style pppm`
`EwaldConfig`	`buck/coul/long <cutoff>` + `kspace_style ewald`

Default cutoffs: short-range 11.0 Å, DSF/Wolf Coulomb 11.0 Å, DSF damping \(\alpha = 0.182\) Å⁻¹.

Melt-Quench Protocol¶

The yang2026_protocol follows the sequence from Yang et al. (2026):

Stage	Ensemble	Temperature	Pressure	Duration
1	NVT	300 K	—	20 ps
2	NPT	300 K	0 GPa	20 ps
3	NPT	\(T_\text{melt}\)	20000 atm (≈ 2 GPa)	100 ps
4	NPT	\(T_\text{melt}\)	0 GPa	100 ps
5	NPT	\(T_\text{melt}\) → 300 K	0 GPa	cooling at 1 K/ps
6	NPT	300 K	0 GPa	100 ps
7	NVT	300 K	—	100 ps

The default melt temperature is 4000 K. Set cooling_steps to (T_high - 300) / timestep to achieve the 1 K/ps cooling rate.

Limitations¶

5 elements only — Na, Ca, B, Si, O; no Al, K, Mg, or other species
No cation–cation pairs for Na–Ca, Na–Si, Ca–Si, etc. — those pairs interact via Coulomb only
Not suitable for aluminosilicate or alkali aluminosilicate glasses