**
Michael R. Salazar**, Union University

A suite of programs called **A**ccelerated **Mol**ecular **D**ynamics with **C**hemistry (** AMolDC**) has been written, tested,
and employed in order to perform adaptive, multilevel QM/MM simulations for
complex chemical processes in the gas-phase. A paper that examines the properties of this new method was published
recently.

Fig. 1 Accuracy in the interpolant as a function of underlying grid density |

Fig. 2 Computational studies of the |

Second, ** AMolDC** was rewritten to submit the
QM jobs in parallel and timing tests were performed. Shown in Figure 1 is a log-log plot of CPU time for various
system sizes of small condensed phase system of water, n-propanol (np),
cyclohexanol (ch), and orthoxylene (ox).
The systems varied in sizes from 1 molecule of each to 6 molecules of
each, giving system sizes from 52 atoms to 312 atoms. The parallel QM calculations were
submitted over an 18 node cluster.
Figure 1 shows the tremendous cost savings associated with performing
interpolations (symbols) over performing parallel QM calulations with no
interpolations (lines). Levels of
theory from B3LYP with cc-pVTZ basis sets to HF with 6-31G** basis sets were
used for the various groups formed in these simulations. Figure 1 also demonstrates that system
sizes of multiple hundreds of atoms may be studied with total CPU times of
about 6 hours while interpolating on DFT and HF potential and force surfaces.

Two manuscripts have been written and submitted to the
Journal of Chemical Physics. The
first manuscript is on the interpolation module, how to perform accurate and
fast interpolations for large chemical systems. The second paper is using this interpolation methodology
within ** AMolDC** to perform computational studies of small hydrated
organic clusters. The papers were
submitted together as back-to-back publications in the same issue.

**References**:

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R.E.; Foley, T.A., *Comput. Math. Appl*.
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