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Department of Physics

Professor Calvin W. Johnson

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Looking for a research project?

My research involves the application of high-performance computing and mathematical models to the quantum wave functions of nuclei and atoms, with an eye to applications to nuclear astrophysics and fundamental interactions.

I work both on high-precision, first principles calculations as well as the exact opposite--what properties arise in many-body systems with random forces?

If you are good at computers, quantum mechanics, and mathematics, you might consider research in my group. While some the introductory projects require only scripting and/or MatLab, more advanced projects require programming in Fortran. Particularly important courses are 317, 410 (may be taken concurrently), 564, 580, and 610.

Several of my undergraduate students have gone on to top Ph.D programs such as at Columbia or Yale, while graduate students have ended up working at national labs such as Los Alamos, Oak Ridge, and Lawrence Livermore.   Ph.D students get their degree in the Computational Science program.

I currently have funding for up to 2 graduate students. Funding depends on the relevance of the project to my grants, and upon the quality of the student. I welcome other students, both graduate and undergraduate.

Current students are working on:
* Large scale calculations of weak (beta-decay and neutrino capture) transitions important for supernova physics;
* Performing cutting-edge first-principles calculations of nuclear properties on leading supercomputers at national laboratories;
* Developing new techniques for computing quantum many-body wavefunctions to take advantage of the newest architectures in computing, such as GPUs (graphical processing units).

Some potential student projects:

Note: these are just general ideas. I would work with you to craft a project suitable to your skills and interests.

Undergraduate (2 semesters, working 6-8 hours/week)

* Improved semi-empirical formula for nuclear masses + improved estimates of theoretical uncertainties in nuclear energies
* Calculation of nuclear collective motion from first principles
* Calculation of resonances in nuclei from first principles
* Computing the nuclear partition function from mean-field theory -- important for nuclear reaction theory
* 1-dimension models of expansion of inhomogeneous universe: can inhomogeneities explain "dark energy"?
* Studying the momentum distribution of linear many-body systems with random interactions

MS students (2-3 semesters, working 10-15 hours/week)

* Relativistic corrections to Coulomb force + RPA calculations of photo absorption (may also be suitable for a good undergraduate).
* Development of a generator-coordinate code as a replacement for standard shell-model diagonalization; optimization using GPUs.
* Looking for "optimal" single-particle states in many-body calculations
* Fits of nuclear interactions to new regions of the chart of the nuclides.
* Computing the binding energies and excitation spectra of positronium complexes ("atoms" made of equal numbers of atoms and positrons) (may also be suitable for a talented undergraduate)
* Scattering of electrons off neutron hydrogen using Gamow scattering states

Computational Science Ph.D students

Ph.D students get their degree in the Computational Science program.

* Sensitivity of ab initio calculations to small changes in interaction
* Development and implementation of scattering for nuclei and atoms into quantum wavefunctions
* Development of "semi-phenomenological" scattering and reaction theory--importing "resonating group method" into phenomenological calculations.

* Development and application of "next-order" random phase approximation as replacement for large-basis shell-model diagonalization.
* Development and application of "cluster models" to nuclear and atomic structure.
* Development of new "symmetries" for nuclear forces with application to nuclear clusters
* Scattering of positrons off atoms

Projects in red may be suitable for funding if available.