Ab initio means from the beginning. Ab initio research in chemical properties and reactivities calls on only essential principles of physics. This semester I have been working on finding properties of lithium fluoride through ab initio calculations. Lithium fluoride is difficult to deal with experimentally, as it vaporizes at very high temperatures. Spectral analysis in the solid phase is not useful, because most of the absorption transitions would be from lattice effects.
Numerous factors limit the accuracy of ab initio calculations.
Most obvious are the limitations imposed by non analytical solutions to the wave differential equations. This limitation is approached by changing the method of solution to a numerical method. However, on the scale of factors that will introduce error to the final results, this factor is not as significant as others. A larger contributor to error is the initial description of the electronic structure of the isolated atoms in the compound. These descriptions are known as a basis set.