Interactions between charged spherical macroions
- Parallel Computational Sciences Dept., MS 1111, Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States)
- Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218 (United States)
Monte Carlo (MC) simulations were used to study the screened interactions between charged spherical macroions surrounded by discrete counterions, and to test previous theories of screening. The simulations were performed in the primitive cell of the bcc lattice, and in the spherical Wigner{endash}Seitz cell that is commonly used in approximate calculations. We found that the Wigner{endash}Seitz approximation is valid even at high volume fractions {phi} and large macroion charges {ital Z}, because the macroion charge becomes strongly screened. Pressures calculated from Poisson{endash}Boltzmann theory and local density functional theory deviate from MC values as {phi} and {ital Z} increase, but continue to provide upper and lower bounds for the MC results. While Debye{endash}H{umlt u}ckel (DH) theory fails badly when the bare charge is used, MC pressures can be fit with an effective DH charge, {ital Z}{sub DH}, that is nearly independent of volume fraction. As {ital Z} diverges, {ital Z}{sub DH} saturates at {ital z}{psi}{sub max}{ital R}{sub {ital m}}/{lambda}, where {ital z} is the counterion charge, {ital R}{sub {ital m}} is the macroion radius, {lambda} is the Bjerrum length, and {psi}{sub max} is a constant of order 10. {copyright} {ital 1996 American Institute of Physics.}
- OSTI ID:
- 279734
- Journal Information:
- Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 13 Vol. 104; ISSN JCPSA6; ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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