Crystal structure prediction by combined optimization of experimental data and first-principles calculation

xrayCrystal structure prediction has been known as one of the most difficult problems, and various prediction methods have been developed so far. Recently, joint optimization of experimental data and the theoretical potential energy calculation has been proposed. In that method, a combined cost function, a sum of reproducibility of experimental data and the potential energy, are optimized. However, combined cost function loses the information of the local minima of each cost functions. We developed a new optimization algorithm, Combined Optimization Method (COM), to overcome this difficulty. For example, it is known that the determination of crystal structure for SiO2 systems is quite difficult due to the existence of a lot of local minimum arrangements. By using the COM, we confirmed that the success rate of crystal structure prediction increases significantly.