It should be noted that the Analytical face index absorption correction is better to use than the traditional Gaussian as the results of the Gaussian absorption correction can be variable depending on the Grid Size used inside Platon (the finer the Grid Size, the longer the calculations take, but the more accurate the absorption correction). The Platon based Analytical absorption correction that WinGX uses gets around this Grid Size problem and is identical in ease of use to the method below, just select the Analytical option. Date: Sun, 13 Sep 1998 17:17:09 +0100 To: L.M.D.Cranswick@dl.ac.uk (L. Cranswick) From: Louis Farrugia Subject: Tutorials Actually there are pro's and cons with Analtyical vs Gaussian The advantages of the analytical correction are (a) it much faster (at least by a factor of 4) (b) it is (theoretically) completely correct assuming the crystal has been measured correctly (virtually impossible to verify) The Gaussian correction does depend for its accuracy on the grid size, as you state. In PLATON, the grid is normally chosen automatically, but you canset it manually as well. This latter option has not yet been implemented in the GUI The disadvantage of the analytical method is that sometimes (perhaps 1 in several thousand goes) the transmission function is incorrectly calculated.