Dear all,

I would like to study the aggregation of particles. Suppose the particles are:
i. water

ii. A (A is an element)

iii. XYZ (X, y, and Z are different elements)

To understand the coordination of A, I conducted an MD simulation with NPT ensemble, obtained trajectories, and then calculated the RDF and the corresponding coordination number of some cases:

1. A-water (with centroid): The first peak is at about r=2 Angstrom, and the coordination number is 6.30

2. A-XYZ (with centroid): The first peak is at r=5 Angstrom, and the coordination number is 0.20

3. A-X: The first peak is at about r=2 Angstrom, and the coordination number is 0.20

I have two questions:

1. How to calculate the "average coordination number" of A?

2. Since the coordination number in the third case above is only 0.2, there is less possibility to see XYZ in the first coordination shell of A. How can I see how the particles water and XYZ aggregate around A? 

Thank you,

Trang