# Polymer Question

1. Jul 21, 2008

### bb1

I'm trying to calculate the structure factor for a polymer melt: S(q)=$$\sum_{k}$$$$\sum_{j}$$$$\epsilon^{i*<q>*<r_{kj}>}$$, but I don't know how to deal with the imaginary exponent...(the rest of the variable don't really matter, because I'm confused about how to deal with the exponent, but q is the scattering vector, and r$$_{kj}$$ is the distance between vectors k and j) my first thought was to multiply by the complex conjugate, but doesn't that just get rid of the exponential altogether, leaving nothing for you to add? I don't understand how I can get any data if I multiply by the complex conjugate. Anyone have any suggestions?

2. Jul 21, 2008

### Mapes

Use Euler's formula and consider only the real part of the trig side (i.e., the cosine). The exponential form makes some calculations easier.

3. Jul 21, 2008

### bb1

Thanks for responding!
I considered that, but it doesn't seem correct to just throw out the complex part...is there something I'm missing?