I had a lecture today that included cell volume and reciprocal cell volume calculations and I did not get it at all. The equations we used are attached.

We went through two problems in class and I was wandering if anyone can shed some light on them at all? like what they are and how you would actually work them out? I have loads of these calculations to do during my course and I really need to get to grips with them

Problem 1

A protein crystallises in a monoclinic unit cell with cell parameters a=100.02Å b=90.57Å c=68.33Å =90.0o =104.48o =90.0o . What is the cell volume (V) and what is the reciprocal cell volume (V*)?

Problem 2

A protein crystallises in an orthorhombic unit cell with cell parameters a=45.69Å b=150.22Å c=75.87Å = = =90.0o . What is the cell volume (V) and what is the reciprocal cell volume (V*)?

 

 

Well, you didn't exactly specify what actually trips you here. You have all the data and all the formulas, you just have to plot the data into formulas.

 

Reciprocal cell is an extremely important concept in crystallography when you're dealing with crystal structures and x-ray diffraction. Normal unit cell identifies actual relations of positions of atoms in crystal structure, but when you put your protein in the difractometer and run it through analysis the diffraction pattern that you'll get as a result would represent the reciprocal unit cell, which is a Fourier transform of the normal unit cell.

 

Could you specify exactly which part are you having issues with?

monoclinic cell volume and reciprocal cell volume