Unilameller DMPC Vesicles Structure Analysis using Parallel Asynchronous Eifferential Evolution

The Separated Form Factors model (SFF) developed previously for analysis of the small angle neutron scattering data, has been extended for numerical study of structure of polydispersed population of unilamellar DMPC vesicles using the small angle synchrotron scattering spectra (SAXS). Parameters of vesicle structure (average radius, polidispersity, bilayer thickness etc.) are fitted by means of the parallel Asynchronous Differential Evolution (ADE) method - the effective global minimization algorithm. Parallel computer implementation of our approach has been done using the MPI technique (Message Passing Interface). The numerical investigation of structure of polydispersed population of unilamellar vesicles of DMPC in the 40% water solution of sucrose has been performed. We show that accounting for the fluctuation of the bilayer thickness provides an agreement of our calculations with experimental data in the right part of SAXS spectra. On the basic of calculations with different models of internal bilayer structure, an appropriate form of the X-ray scattering length density across bilayer has been chosen. We present results of methodical calculations on the multiprocessor cluster (LIT, JINR, Dubna) demonstrating efficiency of the MPI-based parallel computer code of ADE.

vesicles, small angle X-ray scattering, Asynchronous Differential Evolution, global minimization, parallel computing