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Volume 130, Issue 20, 28 May 2009
In this work, lattice Monte Carlo was used to study the effects of crowding on the self-assembly of surfactants. Simulation results show that crowding strongly shifts the critical micelle concentration (CMC) of surfactants from the bulk value. Two effects originated from crowding are found to govern the CMC shift: one is the depletion effect by crowding agents and the other is the available volume for micelle formation. The depletion effects inevitably result in the enrichment of surfactants in crowding-free regions and cause the decrease in CMC. On the other hand, the appearance of crowding agents decreases the available volume for micelle formation, which reduces the conformational entropy and impedes the micelle formation. Three factors, including the radius of crowding agents, the arrangement of crowding agents, and the volume fraction of crowding agents, are considered in this work to study the crowding effects. The trends of CMC shifts are interpreted from the competition between the depletion effects and the available volume for micelle formation.
130(2009); http://dx.doi.org/10.1063/1.3146904View Description Hide Description
The projected Hartree–Fock wavefunctions are recast within the framework of the coupled cluster approach. Instead of state projection we directly symmetry adapt the broken symmetry correlation operator via the group invariant mean. The algebraic form for the cluster amplitudes is connected to the underlying symmetry group by this analytical projection, resulting in the inclusion of symmetry structuredcorrelation effects into the wavefunction. After truncating the corresponding cluster amplitudes to a given order, equations that exploit this sparsity can be derived through the bivariational functional of the normal coupled cluster method. This prescription fills in a methodological gap in the standard couple cluster hierarchy, providing an additional means to incorporate pairing and higher order amplitude contributions.