Development of Computational Methods and their Applications to Studying Nuclear Quantum Dynamics of Complex Molecular Systems

加州大学欧文分校的弗拉基米尔曼德尔什塔姆得到化学系化学理论、模型和计算方法项目的支持，在理论化学领域进行研究。他和他的研究小组开发了新的计算方法，以利用高性能计算机的进步。 他们使用这些新方法在原子水平上研究复杂分子系统的重要和有趣的性质，例如大分子团簇。 目前，他们正在应用这些新方法来了解水分子团簇、离子水分子团簇和氢分子团簇的结构、动力学和光谱学。 Mandelshtam教授在量子动力学方面的研究是发展一种新的方法，称为“准随机分布高斯基”（Quasirandom Distributed Gaussian Basis，QDGB），并将其应用于计算分子和团簇的振动光谱。 QDGB结合了使用高斯基的相对较旧的想法和通过使用准随机序列来分配该基的新方法，该准随机序列对针对所讨论的系统优化的特定分布函数进行采样。 该方法的另一个重要方面涉及使用准蒙特卡罗（QMC）计算涉及势能矩阵元素的所需多维积分的新方法。QMC也是基于准随机序列的。与标准MC不同，它具有上级收敛特性。QDGB被用来研究多原子分子和团簇的振动光谱。此外，Mandelshtam在统计力学方面的研究涉及扩散蒙特卡罗（DMC）方法在研究分子团簇中的能量学、结构、核量子和同位素效应方面的应用。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

Vladimir Mandelshtam of the University of California, Irvine, is supported by the by the Chemical Theory, Models and Computational Methods program in the division of chemistry to conduct research in the area of theoretical chemistry. He and his research group develop new computational methods that take advantage of advances in high-performance computers. They use these new methods to study important and interesting properties of complex molecular systems at the atomic level, for example large molecular clusters. Currently they are applying these new approaches to learn about the structure, dynamics, and spectroscopy of water clusters, ion-water clusters, and hydrogen clusters . The computer programs resulting from this project are made available free of charge to the scientific community.Professor Mandelshtam's research in Quantum Dynamics is concerned with the development of a novel approach under the general title "Quasirandom Distributed Gaussian Basis" (QDGB) and its applications to computations of vibrational spectra of molecules and clusters. QDGB combines the relatively old idea of using a Gaussian basis with the new ways of distributing this basis by using a quasirandom sequence that samples a particular distribution function optimized for the system in question. Another important aspect of the approach involves the new ways of computing the required multidimensional integrals involving the potential energy matrix elements using quasi-Monte Carlo (QMC). QMC is also based on quasirandom sequences. Unlike the standard MC it has superior convergence properties. QDGB is then used to study vibrational spectra of polyatomic molecules and clusters. In addition, Mandelshtam's research in Statistical Mechanics is concerned with applications of the Diffusion Monte Carlo (DMC) method to study energetics, structure, and nuclear quantum and isotope effects in molecular clusters.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.