The DMA method was devised by Prof. Anthony Stone of Cambridge University to describe the charge distribution of a molecule in terms of a multipole expansion around a number of centers.
A multipole series, consisting of a charge, dipole, quadrupole and higher terms is located at each center.
The DMA series are derived from ab initio or density functional theory calculations using Gaussian basis sets.
If the molecular orbitals are written as linear combinations of atomic basis functions the electron density takes the form of a sum of products of the basis functions, called density matrix elements.
This description then includes at each site: The DMA describes the potential at points outside the molecule with an accuracy which is essentially that of the wavefunction, so that its use entails no loss of precision.