目前，通过全原子模拟来研究DNA分子实验现象的机理是分子生物学领域的研究热点之一。然而由于计算量过大，全原子动力学模拟在研究发生在微秒以上的DNA变构现象方面面临挑战。而DNA分子作为高带电聚合电解质，静电作用在DNA相关动力学中起着重要作用。结合现有的极化水和离子模型，本项目拟发展新的基于静电多极势的B-DNA粗粒化力场模型（称为DNA-EMP力场），并进行有效性检测。新力场将用于阐明溶质静电作用在维系B-DNA双螺旋结构中的作用以及水分子和离子对B-DNA不同基团的作用机理。新的力场将应用于以下方面：1）在新力场中引入球形限制势，以阐明生物膜对内部B-DNA分子折叠变构的影响；2）将新力场与粗粒化蛋白模型TMFF力场结合，以揭示组蛋白-DNA在静电多极势下变构的机理。此外，本项目还将采用局部坐标系方法建立DNA由粗粒化模型到全原子模型的转换，实现DNA的结构重构。

Currently, all-atom (AA) dynamics simulation (MD) has been proved to be very useful in studying the DNA systems, which attracts a lot of attention in the field of molecular biology. However, due to high computational cost, it is greatly challenging for AA MD to study the DNA-relevant processes occurring at microsecond level or above. DNA is a highly-charged polyelectrolyte and the electrostatic interaction plays an important role in DNA simulations. Here, based on the electric multipole potential (EMP), we will develop a generic CG model for B-DNA structure, coupling with existing polarizable water and ion models, namely a DNA-EMP force field (FF). Based on available experimental and AA data, validation of the DNA-EMP FF will be assessed by simulating a set of medium structures. Then the roles that electrostatic interaction, polarizable water and ions play in stabilizing the duplex formation of B-DNA will be discussed by the DNA-EMP FF. Interestingly, by adding a spherical confinement potential in the DNA-EMP FF, conformational changes of DNA in cell nucleus or viral capsid can be studied in the virtual sphere. Furthermore, combining the DNA-EMP FF with the existing TMFF protein model, allosteric dynamics of histone-DNA systems can be studied with the EMP. Besides, a local-frame strategy will be adopted to achieve the back mapping from CG configuration to AA representation.