 It's worth noting that some articles and textbook use a slightly different but equivalent version of the equation

where formula_17 is the "i"th component of the vector oriented from the formula_3th atoms to the "k"th calculated via the difference

formula_19

Both equation being strictly equivalent, the definition of the vector can still lead to confusion.The virial pressure can be derived, using the virial theorem and splitting forces between particles and the container or, alternatively, via direct application of the defining equation formula_20 and using scaled coordinates in the calculation.If the system is not homogeneous in a given volume the above (volume averaged) pressure is not a good measure for the pressure.