Mulliken atomic partial charges

The NBO method can be used for ab initio calculations at the HE and any correlated levels as well as for DFT methods. The results do not strongly depend on the size of the basis set, which is one reason that the NBO method has replaced the outdated Mulliken population analysis, for example, for the calculation of atomic partial charges. But there is a price that has to be paid for the advantages. Like any orbital-based method for partitioning the electronic charge into atomic and bonding domains, the choice of the selection procedure has some arbitrary character that needs to be known in order to judge the quality of the results. 

In the version SM5.2PD, the atomic partial charges are taken as the Mulliken-population-analysis net charges (Section 15.6), which are given by Cb - where... 

Before the data of Table 11 are shortly discussed, one has to stress that the partial charges derived from adiabatic infrared intensities are not related to Mulliken charges, virial charges or most other atomic charges used in ab initio theory. The partial charges p are effective charges which in addition to the atomic monopole contribution, cover the atomic dipole contribution as well. They are... 

Table I. Comparison of the partial charges on the individual atoms of H2O and CO2. Mulliken charges as well as the charges derived by fitting the electrostatic potentials (CHELPG charges) in electrons (e).

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