You may wonder why I am insistiong on B.E. Warren's book while there are many other books that describes Debye Waller factors as well. This is because most of the X-ray crystallography books treat Debye-Waller factor as a nuisence that hinders having good intensities at higher two theta and also this factor tend to accumulate other systematic errors when refined by least squares method. But Warren treats the Debye -Waller factor from physical stand point. It gives you the necessary lattice dynamical background. Now a days pair distribution function (PDF) analysis of the total diffraction intensities has become popular. This method includes the missing intensity from the Bragg peaks due to the Debye Waller factor. This missing intensity manifests as diffuse intensity distributed in the reciprocal space that carries valuable information. Warren's book do not discuss this technique although it discusses scattering amorphus materials where similar techniques is used. For PDF analysis of crystalline substances containing disorder and other deviations from perfect crystallinity consult the excellent book by Egami And Billinge " Undeneath the Bragg Peaks etc."

But if you study Warren's book from p. 1 to the last page as I did as a graduate student then you will not be a blind black box user.

Debye Waller factor does not affect the position of the Bragg peaks, it only affects the intensity. Read the text books on X-ray crystallography.

Please can you tell me the name of a text book?

Read for example: B.E. Warren, X-ray diffraction.

The physics behind Debye-Waller factor is:

If the atoms in the crystal were perfectly static (but you know that they are never not even at T = 0) then the intensity of the Bragg reflections are given by the positions of the atoms in the unit cell and the atomic form factors of the constituent atoms. But the atoms are vibrating at finite temperatures. The effect of these vibrations is to take out some intensity from the Bragg peaks smear and distribute these intensities as diffuse intensities on and away from the Bragg peak positions or reciprocal lattice points. These diffuse intensities are called temperature diffuse scattering (TDS) or inelastic phonon scattering. They give information about the dynamics of the atoms constituting the crystal. The intensity taken out from the Bragg peaks by this process increases with momentum transfer or simply with the Bragg angle. This is governed by the factor -B(\sin theta/\lambda)^2 which is called Debye-Waller factor.

The positions of the Bragg peaks are on the other hand are governed by the translational periodicity of the lattice and the shape of the unit cell given by a, b, c, \alpha, \beta, \gamma and of course also depends on the wavelength of the radiation (X-ray) used. You can calculate these positions by Bragg's law.

Now get the book of Warren (buy, borrow or ....) and read from p. 1 to the end!!!

You may wonder why I am insistiong on B.E. Warren's book while there are many other books that describes Debye Waller factors as well. This is because most of the X-ray crystallography books treat Debye-Waller factor as a nuisence that hinders having good intensities at higher two theta and also this factor tend to accumulate other systematic errors when refined by least squares method. But Warren treats the Debye -Waller factor from physical stand point. It gives you the necessary lattice dynamical background. Now a days pair distribution function (PDF) analysis of the total diffraction intensities has become popular. This method includes the missing intensity from the Bragg peaks due to the Debye Waller factor. This missing intensity manifests as diffuse intensity distributed in the reciprocal space that carries valuable information. Warren's book do not discuss this technique although it discusses scattering amorphus materials where similar techniques is used. For PDF analysis of crystalline substances containing disorder and other deviations from perfect crystallinity consult the excellent book by Egami And Billinge " Undeneath the Bragg Peaks etc."

But if you study Warren's book from p. 1 to the last page as I did as a graduate student then you will not be a blind black box user.

Thank you sir for the suggestion. I have gone through the books which you have suggested. Still a few things remain unclear. I have read your book also and it helped a lot.