Hi Bruce and Scott for your valuable comments I am performing refinenments over a serie of cuprates. In this case La2CuO4 should work as a theoretical standard. This is why I wrote to you, but my "interesting" samples don't have much problems. The theoretical standard is the problem! quite crazy! Thanks again I will try Bruce's comments. Best regards Ricardo ------------------------------------------------------------------------- ----- Ing. Quím. Ricardo Faccio Mail: Cryssmat-Lab., Cátedra de Física, DETEMA Facultad de Química, Universidad de la República Av. Gral. Flores 2124, C.C. 1157 C.P. 11800, Montevideo, Uruguay. E-mail: rfaccio@fq.edu.uy Phone: 598 2 9241860 Int. 109 598 2 9290705 Fax: 598 2 9241906 Web: http://cryssmat.fq.edu.uy/ricardo/ricardo.htm