Sylke Boyd, Physics

Sylke Boyd, PhD

Associate Professor, Physics
University of Minnesota, Morris
Office: Science 2315
Phone: (320) 589-6315
sboyd@morris.umn.edu

SB’s Work schedule for fall semester 2013

UMM Weather Station

UMM Student Research in Physics

UMM Undergraduate Research Symposium

Information for students with children

Current Courses: (Spring 2013)

Phys1101 General Physics 1

, Phys3501 Statistical Physics

Office hours for Spring 2013: Tuesday 1:30 – 3:00 pm; Wednesday 12:30-1:30 pm; Thursday 1:00-2:00 pm am, and with arrangement (check my Google calendar for options)

Courses taught recently:

IS1806 Bottomdwellers in an Ocean of Air (F2012), Phys1063 Physics of Weather (F2012), Phys3003 Computer Modeling of Materials F2012, Phys4101 Electromagnetism (F11), Atmospheric Physics Phys2301(F11), (Classical Mechanics (Fall 2010), , Computer Modeling of Materials (Spring 2008), FYS Bottomdwellers in an ocean of air (fall 2006), Physics of Sound and Music (fall 2005)

Courses that may never come to pass:

Alles klommt vom Bergwerk her – A journey to the roots of modern science

This course would take us to Freiberg, Sachsen, Germany. We would explore a beautiful gentle mountain range with an 800-year history of mining.

Curriculum Vitae

Student Research Projects:

Robert Smith’13 RDX elastic constants in RDX and the influence of voids on the elasticity tensor

Chad Reverman’13 Bulk modulus of RDX and the influence of voids

Matthew Kroonblawd’12 Energy distribution in RDX during shock

Jerry Kessler’11 Statistical analysis of 90-year longitudinal weather record in Morris

Johanna Martin’10 Water droplet formation in clouds (MAP 2008/9)

Anna Schliep’07 Dislocations in RDX (GIA, URS 2007 poster)

Sound generation by wind in Strings (UROP, finished, presented as poster at MAAPT Fall 2006 meeting, URS 2007 poster)

Sam Geller’07 Monte Carlo Simulations of Vacancies in a Crystal (GIA, active, presented as poster at MAAPT Fall 2006 meeting)

Matt Gravelle ‘05 Point defects in RDX (UROP and GIA, finished, presented posters at URS and CCTCC, coauthor of publication)

If you are interested in any way to collaborate in a research project please do not hesitate to stop by or drop a line by e-mail.

Research Interests:

My research interest is in computer simulations of materials, including force field development, molecular dynamics and Monte Carlo simulations. Materials modeling allows to address questions that are either hard to access experimentally, or for which experimental results are in need of explanation. To some degree, reliable models can have predictive power, but also provide insight into the mechanisms of otherwise inaccessible phenomena. A successful computer model for a materials problem rests is based on three elements:

The physics of the problem: The question must be relevant, aspects of it not answerable by other means, and backed up with sufficient experimental data.
The software: the success of the model is constrained by computing efficiency. The faster the algorithm, the larger the model, and the longer the times the model can access. A typical molecular dynamics simulation can span a few nanoseconds with sample sizes of a few nanometers. However, many physical problems involve processes on larger time and length scales – limits that need to be pushed. It is crucial to implement parallel computing if helpful, as well as employ other means of pushing these limits, for example by employing a multi-scale approach.

The hardware: We are using the Minnesota Supercomputing Institute’s facilities. Some simulations are performed on a Beowulf cluster with currently 32 CPUs, dedicated exclusively to this purpose. .

Current Projects:

Interfaces under normal and shear stress. Friction is a dissipative phenomenon that has relevance in very many applications as well as in various environmental problems. Static friction is the force which keeps surfaces in contact under stress from sliding relative to each other, while dynamic friction sets in when the surfaces actually move. The transition from static to dynamic friction occurs when the shear stress increases beyond a critical point, detachment occurs, and the contacting surfaces start to slip past each other. The subsequent sliding will easily be maintained by a much lower shear force. Applications in robotics, construction and engineering fields, even processes in geological systems face the challenge of the unpredictability of the onset of sliding. During my research leave in Fall 2008, I am working to develop a comprehensive, multi-scale computer model of frictional processes in order to study the physical processes surrounding the so-called stick-slip transition. I expect that students can work on this project beginning in the spring semester of 2009. This project has ties to the group of Thomas Frauenheim at the Bremen Center for Computational Materials Science in Bremen, Germany.
Water droplet formation in clouds. Water droplets form if the partial pressure of water in the air supersedes the saturation pressure. However, the mechanisms of initial condensation is more complicated and involves nucleation. After the initial droplets are formed, they grow either by continued condensation on their surface, or by merging with other droplets – so-called coalescence. However, in warm cumulus clouds there often is not much time between the initial formation of the cloud and the onset of precipitation, which means that those large rain drops must have formed very fast. The problem is, that the speed of droplet growth in cumulus clouds can not be explained by either one of the two mechanisms above alone. This makes the prediction of the onset and type of precipitation from these clouds difficult – there must be mechanisms beyond condensation and coalescence. Questions of turbulence surrounding a droplet appear to play a role as mechanisms for delivery of additional moisture for condensation. There is a very active area of research, focused on the fluid dynamics involved furthering or limiting droplet growth. This project is developing a computer model for constant-pressure constant-temperature molecular dynamics simulations of water droplets embedded in an air atmosphere. We are studying questions of nucleation, growth rates and coalescence. The model is based on a Lennard-Jones model of water, embedded in a soft hard-sphere fluid (air). This allows to includes the dissipative influence of the air, as well as to study the effect of a droplet with terminal speed onto this medium.

Animations: NPT simulation of a water droplet of 4000 water molecules at 275 K and 1 atm, water particles shown only.

whole system, close-up

Molecular solid RDX: This is a powerful explosive with the caveat of a high sensitivity. The project originates from an initiative from Lawrence Livermore National Lab, trying to solve the problem of stockpile of weapons from the cold-war era. The weapons are aging, and need to be dealt with. Rather than experiment with these stockpiles, a computational initiative has been started to model the materials and their behavior, hence helping to decide the best course of action. In addition, RDX is a material of choice for terrorists due to its large energetic density. Its was used by the shoe bomber Michael Reid in the infamous 2001 air plane incident, but also in the attack on the Marriot hotel in Islamabad, Pakistan, in September 2008. It is important to find inconspicuous methods of detection for such chemicals, and one possibility is the use of Terahertz spectroscopy. This method analyses the spectrum of long-wave infrared radiation in a part of the spectrum that is associated with thermal vibrations of the crystal lattices in conjunction with molecular modes of motion. Our computer model is one of only very few that is able to investigate such coupled modes and predictively model and explain the vibrational spectrum of the substance. Currently my work focuses on the vibrational properties of the substance under various circumstances, such as the presence of large defects and an electric field. In addition, defects in the crystalline lattice provide places at which detonations seem to originate due to their energetically predisposed position. Experimentally, the crystals are produced from solution, and often defects are incorporated during the crystal growth. Limiting the amount of defects can help lower the sensitivity, hence our model studied how the defects are formed, which geometry they have, how easily they heal or diffuse, and how growth conditions influence their concentration. Work has been done on point defects in the molecular solid RDX, voids and dislocations. The project is a collaboration with the group of Peter Politzer at the University of New Orleans. Take a look at the vibrational properties of the RDX molecule

Recent publications and presentations:

Sylke Boyd, Jane S Murray, and Peter Politzer, Molecular dynamics characterization of void defects in crystalline (1,3,5-trinitro-1,3,5-triazacyclohexane), J. Chem. Phys. 131, 204903 (2009).

Sylke Boyd and Kevin J Boyd, A computational analysis of the interaction of lattice and intramolecular vibrational modes in crystalline alpha-RDX, J. Chem. Phys. 129, 134502 (2008).

S. Boyd, K. J. Boyd, Vibrational properties of RDX, presented as poster at the 16^th Conference on Current Trends in Computational Chemnistry (CCTCC) in Jackson, MS, November 1-2, 2007.

S. Boyd, M. Gravelle, Computer Simulations Of Point Defects In Crystalline RDX, presented as poster at the 2006 Gordon Research Conference on Energetic Materials in Tilton, NH, June 18-23, 2006.

Sylke Boyd, Matthew Gravelle, and Peter Politzer, Nonreactive molecular dynamics force field for crystalline hexahydro-1,3,5-trinitro-1,3,5 triazine, , J. Chem. Phys. 124, 104508 (2006).

M. Gravelle, S. Boyd, A computer study of point defects in the RDX crystal, presented as poster at the 14^th Conference on Current Trends in Computational Chemistry (CCTCC) in Jackson, MS, November 4-5, 2005.