An apparatus includes a processor, a memory electrically connected to the processor and that stores instructions, and a storage unit that stores a photoresist molecular model, a surfactant molecular model, an additive molecular model and a solvent molecular model. The processor is configured by the instructions to perform a molecular dynamics simulation of a cell in which are placed photoresist molecules based on the photoresist molecular model, surfactant molecules based on the surfactant molecular model, additive molecules based on the additive molecular model, and solvent molecules based on the solvent molecular model, and compute a number of first surfactant molecules located in the cell in a vicinity of an interface between a photoresist pattern that includes the photoresist molecules and a solvent that includes the solvent molecules, and a number of second surfactant molecules located in the cell in a vicinity of a surface of the solvent.