Hi, I am looking for a code that will perform a matrix rotation around a desired point and NOT about an axis for example. I am looking for references in this area that would help me achieve this rotation. I know it is possible, but cannot find anything relevant in the literature.

Thanks

Well this is a simple Matrix multiplication, you take the standart rotation matrix with the disired Angle and multiply it with the given Matrix. Stuff like that can be found for example in OpenGL guides, or graphic programming guides which also show stuff like the bresenham algorithms, and such. Just Google for Bresenham and you'll going to find a couple of those, which might also keep on going towards more graphic stuff. Literature wise check out the OpenGL Redbook. Even though those kind of Manipulations are already implemented in OpenGL, it will show you how to use those.
Which is your disired Programming Language? I did this kind of stuff using C++/QT/OpenGL in a course at my college.

I have some code that I have inherited which performs a 3D rotation by taking a central point a COM if you like and then determining a vector which defines a point in the system, an atom for example. Then this vector is simply rotated by theta and phi, using matrix rotations. I have the code, but I wish to have a reference to where the code came from and how it was derived.

rotations always occur around an axis. The concept of rotation around a single point is invalid, except insofar as that point lies on the axis of rotation.

There are two components:

One is a rotation about phi, which is with respect to an axis and this simply takes the form:

| cos (phi) -sin (phi) 0 |
| sin (phi) cos (phi) 0 |
| 0 0 1 |

That I agree is rotation about a z axis.

Then there is the theta part which is much more complex. This I have broken down into some of the constituent parts. I cannot find anywhere on the wen where this might have come from. The summation of A, B and C leads to a rotation about theta, assuming some arbitrary axis, which one can assume is that same as before.

A
==
| sin^2(theta)*(1-cos(theta)) (1-cos(theta))cos(theta)sin(theta) 0 |
| -sin(theta)cos(theta)*(1-cos(theta)) cos^2(1-cos(theta)) 0 |
| 0 0 0 |

B
==
| 0 0 -cos(theta)*sin(theta) |
| 0 0 sin^2(theta) |
| cos(theta)sin(theta) sin^2(theta) 0 |

C
==
| cos(theta) 0 0 |
| 0 cos(theta) 0 |
| 0 0 cos(theta) |