1. One or more non-transitory computer-readable media storing computer-executable instructions for causing one or more processors to perform a method, the method comprising: extracting effective thermal conductance and effective thermal capacity for each region of a plurality of regions of a layout design, the layout design corresponding to at least a portion of an integrated circuit, and the effective thermal conductance for a region in a metal layer being determined based at least on density information of metal interconnect lines within the region and having components dependent on directions of the metal interconnect lines; constructing a thermal circuit based on the effective thermal conductance, the effective thermal capacity, and heat information of thermal nodes, the heat information of thermal nodes determined based on an electrical simulation on the integrated circuit; and performing a thermal simulation on the thermal circuit to determine temperature information of the thermal nodes; wherein the effective thermal capacity is determined based on mechanical property information, the mechanical property information comprising Young's modulus, Poisson factors, thermal expansion coefficients, or any combination thereof.