Computational Modeling of Chemical Reactions in Ultrasound Baths

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Ultrasound baths are used in many chemical laboratories for shredding and mixing of substances. In addition, sonochemistry, i.e. the initiation of chemical reactions by ultrasound, is an intriguing branch of chemistry that enjoys increasing popularity. Although it is known that molecules in ultrasound baths are exposed to mechanical shear forces, temperatures of several thousand Kelvin and pressures of more than a thousand atmospheres, no computational method for the simulation of molecules in ultrasound baths exists until the present day. Hence, a rational design of sonochemical reactions is impossible, complicating the planning and optimization of these processes.In this project, a computational method for the simulation of molecules in ultrasound baths is developed. Initially, the focus lies on polymers, since ultrasound baths are a well-established method for the unfolding and rupture of polymer strands and a plethora of experimental observations against which the new method can be benchmarked have been described. In the later stages of the project, reactions in organic sonochemistry will be investigated as well.For the description of molecules in ultrasound baths, Molecular Dynamics (MD) and Born-Oppenheimer Molecular Dynamics (BOMD) simulations are used. In addition to the explicit classical simulation of a polymer strand that is exposed to a shock wave upon collapse of a cavitational bubble, during the course of the project, established methods for the simulation of molecules under external forces as well as high temperatures and pressures will be applied. In the BOMD simulations, for example, mechanical forces will be applied via the EFEI (External Force is Explicitly Included) approach and pressures via the X-HCFF (eXtended Hydrostatic Compression Force Field) method. Through an appropriate combination of these factors as well as the propagation of the molecules in time, the chemical processes in ultrasound baths can be modeled realistically. The aim of this project is the correct reproduction of the points of material failure in polymer strands that are exposed to ultrasound as well as the accurate prediction of the reaction products in organic sonochemistry.