Discrete stochastic variables

A stochastic process is the time evolution of a random variable or a collection of random variables. The range of all possible values is called the state space. Depending on the nature of a random variable, its state space may be continuous or discrete. Examples of discrete random variables in physical chemistry include the configurations of a lattice model, quantized vibrational energy levels, nodes of a network representing configurations of a protein, or integer numbers of species in a biochemical reaction network. Examples of continuous random variables include position along a dihedral angle coordinate or kinetic energies of gas molecules.