Bending rigidities of surfactant bilayers using self-consistent field theory

Abstract

Self-consistent field (SCF) theory is used to find bending moduli of surfactant and lipid bilayers. Recently, we successfully applied low-memory search methods to solve the SCF equations. Using these we are now able to directly evaluate the Gaussian bending modulus for molecularly detailed models of bilayers by evaluating the excess Helmholtz energy of tensionless bilayers in a (part of the) Im3m cubic phase. The result prompted us to reconsider the protocol that has been used thus far to find the mean bending modulus kc and Gaussian bending modulus k[overline]. With respect to previous predictions, the value of kc is reduced by a factor of two and the Gaussian bending modulus is less negative and much closer to zero. In line with experimental data we now find that k[overline] can also become positive. In this paper we use the non-ionic surfactants series of the type CnEm for illustration.