1. A computer-implemented method to calculate a total force on an instance in an instance placement for an integrated circuit on a chip, comprising: computing a force between a first instance and an element, the element being at least one of another instance in the integrated circuit and a chip resource on the chip, the force being a function of the distance between the instance and the element; partitioning a neighborhood of the first instance into a plurality of neighborhood areas including a short range neighborhood area and a medium range neighborhood area based on the distance to the first instance, wherein the neighborhood areas are determined by the area required to legalize the usage of instances surrounding the first instance; computing a plurality of neighborhood forces including a short range neighborhood force on the first instance as a function of the forces between the first instance and elements of the short range neighborhood area and a medium range neighborhood force on the first instance as a function of the forces between the first instance and elements of the medium range neighborhood area; and computing a total force on the first instance by a weighted sum of the neighborhood forces, wherein the neighborhood areas comprise a long range neighborhood and wherein the weight for a long range neighborhood force is inversely proportional to the density of instances in the short range neighborhood area, wherein the method is executable by at least one processor.