### Excluded volume fit in CRYSOL

Posted:

**2013.12.18 21:43**Hi

In the CRYSOL paper it lists only 2 adjustable parameters in the fit, the density of the hydration layer and the effective atomic radius, r0. However, there are 3 adjustable parameters in the software, the density of the hydration layer, the

My questions are:

1). Why are there 3 adjustable parameters in the code while the paper only has 2. Specifically, why is excluded volume an adjustable parameter when the paper clearly states that excluded volume is a function of r0?

2). Does the parameter "Ra" correspond to r0?

Thanks

In the CRYSOL paper it lists only 2 adjustable parameters in the fit, the density of the hydration layer and the effective atomic radius, r0. However, there are 3 adjustable parameters in the software, the density of the hydration layer, the

*optimal*atomic radius,Ra, and the excluded volume. The paper states r0 is "a variable parameter that can be used to change the displaced volume per atomic group and thus to adjust the total excluded volume".My questions are:

1). Why are there 3 adjustable parameters in the code while the paper only has 2. Specifically, why is excluded volume an adjustable parameter when the paper clearly states that excluded volume is a function of r0?

2). Does the parameter "Ra" correspond to r0?

Thanks