This paper presents a United Atom (UA) force field for simulating hydrocarbon molecules in bituminous materials, integrating explicit hydrogens into beads with their parent atom. This method simplifies all-atom molecular models, significantly accelerating Molecular Dynamics (MD) simulations of bitumen by 10 to 100 times. Key advantages include halving the particle count, eliminating complex hydrogen interactions, and decreasing the degrees of freedom of the molecules. Developed by mapping forces from an all-atom model to the centers of mass of UA model beads, the force field ensures accurate replication of energies, forces, and molecular conformations, mirroring properties like pressure and density. It features 17 bead types and 287 interaction types, encompassing various hydrocarbon molecules. The UA force field's stability, surpassing all-atom models, is a notable achievement. This stability, stemming from smoother potential energy surfaces, leads to consistent property measurements and improved stress tensor accuracy. It enables the extension of MD simulations to larger spatiotemporal scales, crucial for understanding complex phenomena such as phase separation in bituminous materials. This foundational work sets the stage for future developments, including refining parameters and introducing new bead types, to enhance the modeling capabilities of the force field, thereby advancing the application and understanding of bituminous materials.

中文翻译：

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引入力匹配的联合原子力场以探索沥青分子动力学模拟中更大的时空域

本文提出了一个联合原子 (UA) 力场，用于模拟沥青材料中的碳氢化合物分子，将显式氢与其母原子整合到珠子中。该方法简化了全原子分子模型，将沥青的分子动力学 (MD) 模拟速度显着加快了 10 至 100 倍。主要优点包括粒子数减半、消除复杂的氢相互作用以及降低分子的自由度。该力场通过将全原子模型的力映射到 UA 模型珠的质心而开发，可确保能量、力和分子构象的精确复制，反映压力和密度等特性。它具有 17 种珠子类型和 287 种相互作用类型，涵盖各种碳氢化合物分子。 UA力场的稳定性超越了全原子模型，是一项了不起的成就。这种稳定性源于更平滑的势能表面，可实现一致的特性测量并提高应力张量精度。它能够将分子动力学模拟扩展到更大的时空尺度，这对于理解沥青材料中的相分离等复杂现象至关重要。这项基础工作为未来的发展奠定了基础，包括细化参数和引入新的珠子类型，以增强力场的建模能力，从而促进沥青材料的应用和理解。