There exists graphical methods of indexing tetragonal (including body centered tetragonal, bct). You can use Hull-Davey chart or a Bunn chart. The methods have been illustrated in the book "Elements of X-ray diffraction" by B.D. Cullity in section 10-4, p. 330. In similar graphical method you can also index hexagonal and rhombohedral systems. Indexing these system is fairly straightforward because of the small number of unknown parameters. For orthorhombic, monoclinic and triclinic systems because of the larger number of unknown parametrs that are involved, the indexing becomes very difficult. But you can use FULLPROF to index the pattern as well. But for this you must know the approximate lattice parameters and then ask the program to refine the parameters to fit the positions of the diffraction peaks. By this program you can index any structure provided that you have good starting lattice parameters.

There exists graphical methods of indexing tetragonal (including body centered tetragonal, bct). You can use Hull-Davey chart or a Bunn chart. The methods have been illustrated in the book "Elements of X-ray diffraction" by B.D. Cullity in section 10-4, p. 330. In similar graphical method you can also index hexagonal and rhombohedral systems. Indexing these system is fairly straightforward because of the small number of unknown parameters. For orthorhombic, monoclinic and triclinic systems because of the larger number of unknown parametrs that are involved, the indexing becomes very difficult. But you can use FULLPROF to index the pattern as well. But for this you must know the approximate lattice parameters and then ask the program to refine the parameters to fit the positions of the diffraction peaks. By this program you can index any structure provided that you have good starting lattice parameters.

Dear Volker Klemm,

I am really appreciate your help for this question as well as my previous questions. Thank you for your time.

@Tapan Chatterji- Thank for your answer also.

I agree with you that the Tapan's answer is very good, but in addition you can also find information on analysis of the powder method for lower symmetries such as hexagonal, tetragonal and orthorhombic in Chapter 5 of "X-ray diffraction" by B. E. Warren

Powder pattern indexing is an age-old problem and has been discussed in the literature intensively. When the unit cell needs all six cell parameters then all simple graphical methods do not work. In such cases there exists methods and computer programs that can be tried. The method of powder diffraction indexing is known variously as Ito's method, de Wolff's method, Visser's method, or Zone-indexing. The method first proposed by Runge in 1917 and rediscovered by Ito (1949, 1950). It was then further developed by de Wolff (1957, 1958, 1963) and incorporated in a computer program by Visser (1969). With the advances in computer speed it became apparent that the solution for indexing of powder pattern can be found by exhaustively searching the available parameter space in small increments and looking for agreement between computed and observed 1/d^2. This lead to the famous program DICVOL91. The program TREOR90 is based on semi-exhaustive method. Other indexing program are listed by Shirley (1983) and Werner (2002) and on the IUCr CCP14 site http://www.ccp14.ac.uk.