A technique for calculating particle systems containing rigid and soft parts

In this paper, a method was proposed that can simulate the systems containing both rigid and soft parts with rigid body constraints. The idea was to consider the characteristics of rigid parts in their center of mass with three rotational degrees of freedom. In order to compute the systems containing both flexible and rigid parts, standard techniques in molecular dynamics were utilized for flexible parts. However, special procedures were proposed and formulated for rigid parts. Some details on the implementation of the proposed algorithm on GPU were also presented. Next, two case studies were solved. In the first example, a ball mill with the rigid particle of different shapes was considered and the performance of the proposed algorithm was checked and compared with the results obtained from others. In the second example, different self-assembly phases of a mixed rigid and non-rigid polymer molecule with Lennard–Jones pairwise interaction were studied. It was shown that the obtained self-assembly phases were identical to those reported by other researchers.