4f-in-core large-core model core potentials (LC-MCP), in which the effects of open shell 4f electrons as well as those of other electrons up to 4d were replaced with MCPs, were developed for the lanthanide trivalent ions. In order to achieve desired accuracy, the LC-MCPs were calibrated using static quantum-chemical calculations for LnF(3), and tested by ab initio molecular dynamics simulation on the hydration dynamics of La3+. Comparing calculated results using the 4f-in-core LC-MCPs with those employing 4f-in-valence MCPs, we found that the 4f-in-core LC-MCPs require less computational costs than the 4f-in-valence MCPs with keeping enough accuracy for describing chemical properties of trivalent lanthanide systems. (C) 2011 Elsevier B. V. All rights reserved.