Theoretical Studies of Intermolecular Forces

特拉华州大学的Krzysztof Szalewicz教授获得了化学系化学理论、模型和计算方法项目的奖项，以研究分子之间的作用力。虽然这种力比分子内部的化学键合力弱十倍，但它们决定了大多数材料和生物体的性质。分子间力可以使用Szalewicz和同事开发的方法计算。一个适合于这种计算结果的整体解析函数叫做它的力场。一旦知道了分子团簇、凝聚相或生物聚集体的力场，就可以通过求解原子运动的经典或量子方程来预测这些系统的所有性质。这项研究的一个目标是增加对这些性质对分子间力的具体依赖性的理解，这为设计新材料提供了指导。另一个目标是改进算法和计算方法，以便对比现在可能大几倍的系统进行第一原理预测。待计算的基于物理的力场有望改变生物分子模拟和材料建模与设计领域。这种力场也与计量标准和解释光谱或散射测量有关，为构建大气模型提供数据，并有助于理解星际分子云中的过程。新的晶体结构预测方法可以帮助制药行业寻找药物的多晶型形式。Szalewicz研究的首要目标是增加对依赖于分子间力的物理、化学和生物化学现象的基于第一性原理的理解。高精度的分子间力场可以使用Szalewicz小组共同开发的自适应微扰理论（SAPT）来计算。SAPT提供了一种独特的能力来解释依赖于分子间力的四个基本的物理机制，导致静电，交换，诱导和分散的相互作用能的贡献方面的属性。基于密度泛函理论（DFT）描述的单体的SAPT，一种表示为SAPT（DFT）的方法，与SAPT一样精确，但计算效率更高。理论的发展包括在DFT框架内预测精确色散能的非局部相关泛函的工作，可以与精确色散能配对的改进的DFT方法，Szalewicz小组早期开发的自动力场生成方法对柔性单体的扩展，从第一原理预测晶体结构的多组分方法，以及基于从头计算的单体性质的通用力场，这是向基于物理学的生物分子力场方向迈出的一步。该奖项反映了NSF的法定使命，并被认为是值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估的支持。

Professor Krzysztof Szalewicz of the University of Delaware is supported by an award from the Chemical Theory, Models and Computational Methods program in the Division of Chemistry to study forces acting between molecules. Although such forces are about ten times weaker than the chemical bonding forces acting inside molecules, they determine properties of most materials and living organisms. Intermolecular forces can be calculated using methods developed by Szalewicz and coworkers. A global analytic function fitted to results of such calculations is called its force field. Once the force field is known for a molecular cluster, condensed phase, or biological aggregate all properties of such systems can be predicted by solving the classical or quantum equations for atomic motions. One goal of this research is to increase the understanding of the dependence of these properties on specifics of intermolecular forces, which provides guidance in designing new materials. Another goal is to improve algorithms and computational methods to make first-principles predictions for systems several times larger than it is now possible. The physics-based force fields to be calculated hold promise for transforming the field of biomolecular simulations and of materials modelling and design. Such force fields are also relevant for metrology standards and for interpreting spectroscopic or scattering measurements, provide data for constructing models of the atmosphere, and help to understand processes in interstellar molecular clouds. The new crystal structure predictions methods can assist pharmaceutical industry in finding polymorphic forms of drugs.The overarching goal of Szalewicz's research is to increase the first-principles-based understanding of physical, chemical, and biochemical phenomena that depend on intermolecular forces. High-accuracy intermolecular force fields can be computed using symmetry-adapted perturbation theory (SAPT), which was co-developed by Szalewicz's group. SAPT provides a unique ability to interpret properties dependent on intermolecular forces in terms of the four fundamental physical mechanisms that lead to the electrostatic, exchange, induction, and dispersion contributions to the interaction energies. SAPT based on monomers described by density-functional theory (DFT), a method denoted as SAPT(DFT), is as accurate as SAPT, but computationally more efficient. The developments of theory include work on nonlocal correlation functionals which predict accurate dispersion energies within the DFT framework, improved DFT methods that can be paired with accurate dispersion energies, extensions of the automated force-field generation method developed earlier in Szalewicz's group to flexible monomers, multicomponent methods for crystal structure predictions from first principles, and universal force fields based on ab initio computed monomer properties, a step in the direction of physics-based biomolecular force fields. Several applications of these methods to systems of current experimental, observational, or technological interest are also pursued.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.