# Robert Brown

### **Lecturer of Physics**

### Overview

Prof. Robert G. Brown is interested in using algebraic and statistical methods to study a wide range of equilibrium and nonequilibrium problems. With collaborator Dr. Mikael Ciftan, Dr. Brown has developed new Monte Carlo Langevin equation-based techniques that allow dynamic/nonequilibrium and static/equilibrium phenomena to be studied on the same footing. His recent work includes algebraic and computational studies in dynamic and static critical phenomena in quantum optics and magnetism. In earlier work, Dr. Brown also developed a generalized (non-muffin-tin) stationary multiple scattering theory including applications to band theory and quantum chemistry. This work formally eliminates the muffin-tin approximation from KKR-type band theory and its equivalents in quantum chemistry, without the need for so-called "near field" corrections.

### Selected Grants

Monte Carlo Studies of Continuous Hamiltonian Systems Coupled to Dissipative Mechanisms awarded by Army Research Office (Co-Principal Investigator). 2001 to 2005

Brown, R. G., and M. Ciftan. “Critical behavior of the helicity modulus for the classical Heisenberg model.” *Physical Review B Condensed Matter and Materials Physics*, vol. 74, no. 22, Dec. 2006. *Scopus*, doi:10.1103/PhysRevB.74.224413.
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Brown, R. G. “Finite size scaling of the helicity modulus of the classical Heisenberg ferromagnet.” *Physical Review Letters*, 2005.

Brown, R. G., and M. Ciftan. “Brown and ciftan reply.” *Physical Review Letters*, vol. 78, no. 11, Jan. 1997, p. 2266. *Scopus*, doi:10.1103/PhysRevLett.78.2266.
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Brown, R. G., and M. Ciftan. “Dynamic critical exponents and sample independence times for the classical Heisenberg model.” *Physical Review. B, Condensed Matter*, vol. 54, no. 22, Dec. 1996, pp. 15860–74. *Epmc*, doi:10.1103/physrevb.54.15860.
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Brown, R. G., and M. Ciftan. “High-precision evaluation of the static exponents of the classical Heisenberg ferromagnet.” *Physical Review Letters*, vol. 76, no. 8, Feb. 1996, pp. 1352–55. *Epmc*, doi:10.1103/physrevlett.76.1352.
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Brown, R. G., and M. Ciftan. “Critical scaling of the dynamic critical exponents of the classical Heisenberg ferromagnet.” *Phys. Rev.*, vol. B54, 1996.

Brown, R. G. “Softwares hard questions.” *Scientific American*, vol. 272, no. 1, Jan. 1995, pp. 8–8.

Brown, R. G., and M. Ciftan. “Statistical microdynamics of extended systems in natural function spaces.” *International Journal of Quantum Chemistry*, vol. 48, no. 27 S, Jan. 1993, pp. 363–75. *Scopus*, doi:10.1002/qua.560480837.
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Ciftci, A. K., et al. “Elementary integral of Bessel functions.” *Physical Review. B, Condensed Matter*, vol. 41, no. 5, Feb. 1990, pp. 3242–43. *Epmc*, doi:10.1103/physrevb.41.3242.
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Brown, R. G., and M. Ciftan. “N-atom optical Bloch equations: A microscopic theory of quantum optics.” *Physical Review. A, General Physics*, vol. 40, no. 6, Sept. 1989, pp. 3080–105. *Epmc*, doi:10.1103/physreva.40.3080.
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