Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Discontinuous Molecular Dynamics for Semi-Flexible and Rigid Bodies   A general framework for performing event-driven simulations of systems with
semi-flexible or rigid bodies interacting under impulsive torques and forces is
outlined. Two different approaches are presented. In the first, the dynamics
and interaction rules are derived from Lagrangian mechanics in the presence of
constraints. This approach is most suitable when the body is composed of
relatively few point masses or is semi-flexible. In the second method, the
equations of rigid bodies are used to derive explicit analytical expressions
for the free evolution of arbitrary rigid molecules and to construct a simple
scheme for computing interaction rules. Efficient algorithms for the search for
the times of interaction events are designed in this context, and the handling
of missed interaction events is discussed.

29
The categories of this paper are: funct-an
26
The categories of this paper are: bayes-an
35
The categories of this paper are: mtrl-th
33
The categories of this paper are: plasm-ph
1
The categories of this paper are: cs
7
The categories of this paper are: hep-th
24
The categories of this paper are: dg-ga
18
The categories of this paper are: econ
34
The categories of this paper are: chem-ph
11
The categories of this paper are: hep-lat
8
The categories of this paper are: hep-ex
2
The categories of this paper are: math
5
The categories of this paper are: gr-qc
23
The categories of this paper are: solv-int
3
The categories of this paper are: physics
19
The categories of this paper are: eess