TraPPE-zeo: Transferable Potentials for Phase Equilibria Force Field for All-Silica Zeolites

The transferable potentials for phase equilibria (TraPPE) force field is extended to all-silica zeolites. This novel force field is parametrized to match the experimental adsorption isotherms of n-heptane, propane, carbon dioxide, and ethanol with the Lennard-Jones parameters for sorbate–framework interactions determined in a consistent manner using the Lorentz–Berthelot combining rules as for other parts of the TraPPE force field. The TraPPE-zeo force field allows for accurate predictions for both adsorption and diffusion of alkanes, alcohols, carbon dioxide, and water over a wide range of pressures and temperatures. In order to achieve transferability to a wider range of molecule types, ranging from nonpolar to dipolar and hydrogen-bonding compounds, Lennard-Jones interaction sites and partial charges are placed at both the oxygen and the silicon atoms of the zeolite lattice, which allows for a better balance of dispersive and first-order electrostatic interactions than is achievable with the Lennard-Jones potential used only for the oxygen atoms. The use of the Lorentz–Berthelot combining rules for unlike interactions makes the TraPPE-zeo force field applicable to any sorbate as long as the relevant TraPPE sorbate–sorbate parameters are available. The TraPPE-zeo force field allows for greatly improved predictive power compared to force fields that explicitly tabulate the individual cross-interaction parameters.相平衡可转移势（TraPPE）力场被扩展至全硅沸石体系。该新型力场通过拟合正庚烷、丙烷、二氧化碳与乙醇的实验吸附等温线完成参数化，其吸附质-骨架相互作用的伦纳德-琼斯（Lennard-Jones, LJ）参数，遵循与TraPPE力场其余部分一致的洛伦兹-贝塞洛特（Lorentz–Berthelot）混合规则进行统一确定。TraPPE-zeo力场可在宽广的压力与温度区间内，精准预测烷烃、醇类、二氧化碳及水的吸附与扩散行为。为实现对从非极性、偶极性到氢键类化合物等更广范围分子类型的可转移性，该力场将伦纳德-琼斯作用位点与部分电荷同时布置于沸石晶格的氧原子与硅原子上；相较仅在氧原子上采用伦纳德-琼斯势的方案，其可更好地平衡色散相互作用与一级静电相互作用。由于针对异种相互作用采用了洛伦兹-贝塞洛特混合规则，只要具备对应TraPPE力场的吸附质-吸附质相互作用参数，TraPPE-zeo力场即可适用于任意吸附质体系。相较于显式列出各交叉相互作用参数的力场，TraPPE-zeo力场的预测性能得到了显著提升。