Interaction potential of the manganese dimer in its lowest spin-polarized (11)Sigma(+)(u) state is investigated ab initio using the coupled cluster method including single, double and non-iterative triple excitations. Special care is taken of the core correlation and the basis set saturation, including extrapolation to the complete basis set limit. The calculations reveal weak dispersion bonding and the following potential parameters R-e approximate to 3.69 angstrom, D-e approximate to 540 cm (1), D-0 approximate to 520 cm (1), omega(e) approximate to 40 cm 1. Agreement with the experimental and other theoretical data is discussed. (C) 2008 Elsevier B.V. All rights reserved.