First, may I assume that you are referring to the ATZ coefficient in fullprof related to quantitative phase analysis?  ATZ is defined on page 91 of the fullprof manual, however fullprof calculates ATZ automatically for you, and you could just look at it in the output if you wanted to:

ATZ = Z * MW * f^2 / t

Z: Number of formula units per cell

Mw= molecular weight

f: Used to transform the site multiplicities used on line 11-41 to their true values. For a stoichiometric phase f=1 if these multiplicities are calculated by dividing the Wyckoff multiplicity m of the site by the general multiplicity M. Otherwise f=Occ.M/m, where Occ. is the occupation number given in LINE 25.

t: Is the Brindley coefficient that accounts for microabsorption effects. It is required for quantitative phase analysis only. When different phases have similar absorption (in most neutron uses), this factor is nearly 1 (in such case ATZ=Z.Mw.f2

). The Brindley coefficient is directly read in one of the following lines.

Thanks Ryan,

myself just started studying crystallography.

  f: Used to transform the site multiplicities used on line 11-41to their true values.

what do you mean by line 11-40 ?pls clarify 

 Hi

Throughout the fullprof manual/guide, there are references to various "lines" which are examples chunks of a working pcr input file for fullprof.  It is best to look through the manual which is freely available online if you have not.  

Maybe it would be simpler if you explained what you are trying to do?  As I said, fullprof will calculate this ATZ for you.  It is just a coefficient used in the calculation of phase fractions.

Ryan

i was studying fullprof.some observations i found .i am writing it here.pls go through it and add your corrections .

The molecular weight of pyrochlore is 800.There is an option in full prof to calculate ATZ automatically.I made a PCR file using graphical interface.i made ATZ calculate automatically.After refinement i opened pcr file in text editor.there it is written ATZ value as around 80000.

(i request you to generate pcr files from the examples given by fullprof using graphical user interface.pls check your ATZ value in .pcr file by opening it in text editor.for Ceo2 example file the ATZ supposed to be 688.480 )

Again i generated a pcr file og EuIrO using old version of fullprof graphical user interface.This time i got ATZ value around 1600. 1600/800=2.If we search literature we will see two statements

1.The space group of the ideal pyrochlore structure is Fd-3m and there are eight molecules per unit cell(Z=8).

2.Pyrochlore belongs to the space group Fd-3m with two formula units (A2B2O7) per primitive unit cell.

These two statements are equivalent.(but still it is not clear for me.if you can comment  on it pls do )

In the ATZ definition given by fullprof we need to take z=2 (and not z=8).

currently myself is doing refinement with  JANA.There is one cookbook.

http://jana.fzu.cz/workshops/Jana2006%20Cookbook.pdf

They explained each steps for refinement very well.