Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Electrostatics and aggregation: how charge can turn a crystal into a gel   The crystallization of proteins or colloids is often hindered by the
appearance of aggregates of low fractal dimension called gels. Here we study
the effect of electrostatics upon crystal and gel formation using an analytic
model of hard spheres bearing point charges and short range attractive
interactions. We find that the chief electrostatic free energy cost of forming
assemblies comes from the entropic loss of counterions that render assemblies
charge-neutral. Because there exists more accessible volume for these
counterions around an open gel than a dense crystal, there exists an
electrostatic entropic driving force favoring the gel over the crystal. This
driving force increases with increasing sphere charge, but can be counteracted
by increasing counterion concentration. We show that these effects cannot be
fully captured by pairwise-additive macroion interactions of the kind often
used in simulations, and we show where on the phase diagram to go in order to
suppress gel formation.

10
The categories of this paper are: q-bio
24
The categories of this paper are: dg-ga
17
The categories of this paper are: q-fin
33
The categories of this paper are: plasm-ph
11
The categories of this paper are: hep-lat
26
The categories of this paper are: bayes-an
13
The categories of this paper are: quant-ph
8
The categories of this paper are: hep-ex
1
The categories of this paper are: cs
25
The categories of this paper are: patt-sol
15
The categories of this paper are: nucl-ex
37
The categories of this paper are: supr-con
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The categories of this paper are: eess
23
The categories of this paper are: solv-int
2
The categories of this paper are: math
14
The categories of this paper are: math-ph