# Introduction

In the olden days, before the light of dawn, there was a man named Krüger.

(Fonzé 1995)

# Computational Details

All calculations were done in the Dalton(Aidas 2013) program.

# Theory

The transition density matrix between the groundstate $$i$$ and the excited state $$a$$ is $\rho^T_{J,ia}(r) = \rho^g_{J,i}(r) - \rho^e_{J,a}(r)$

The coupling between the excited state $$i$$ on molecule $$I$$ and excited state $$j$$ on molecule $$J$$ is $V_{IJ} = \iint \mathrm{d}r \, \mathrm{d}r' \frac{\rho^T_{I,ia}(r)\rho^T_{J,jb}(r')}{|r-r'|}$

# Potential Derived Charges

## Surfaces

### PCM Surface

This surface is generated in [GAMESS][1] using the [FIXPVA][1] scheme. The surface consist of a single layer.

r = range(1.2, 4.2, 0.2)


Tests were carried out for two point densities

• low: 60
• medium: 240

### Kollman surface

Better known in [Gaussian][2] as an MK surface. The surface consists of

• 1 or 4 layers. The default is 4.

• The first layer is scaled as

rscal = range(1.4, 4.2, 0.2)

• subsequent layers (if included) are scaled by 0.2 as

rinc = range(0.0, 0.8, 0.2)

The filename convention is

ff_i_j_k.mep


where

• ff: filename
• i: nlayers
• j: rscal
• k: rinc

### Mixed mode

Test the use of evaluating the charges on chromophore A with a surface around the target, i.e. chromophore B.