The aim of this project is to determine which cell models produce realistic results in simulations of atrial fibrillation. Relevant questions include: Is a complex cell model necessary, or will a simplified model suffice? What other factors (heterogeneity, pacing) must be considered? Simulations for this project will be performed using the software Py4C, and will involve testing the behavior of various cell models, adjusting parameter values for these models, varying stimulation protocol, and testing the effects of anisotropy and heterogeneity.