Topic: Van der Waals forces between molecules (their dependance on distance) (Read 5830 times)

Marija · « **on:** January 03, 2010, 07:49:13 AM »

Hi!

I have a problem regarding Van der Waals forces between two molecules. I understand the basics of their origin, my question is how do they depend on distance. In one of my scripts it is said that they decrease with growing distance as 1/r⁶ and in another script it is said that the dependence is 1/r⁷.
I was browsing on google, but I didin't find my answer, so I'll really appreciate your help. Thanks in advance.

renge ishyo · « **Reply #1 on:** January 03, 2010, 01:30:36 PM »

Most treatments I have seen of the Van Der Waals force have it's strength varying with distance as 1/r⁶.

Marija · « **Reply #2 on:** January 03, 2010, 04:31:30 PM »

Thanks.

Yggdrasil · « **Reply #3 on:** January 05, 2010, 02:59:33 AM »

The strength of the van der Waals force varies with 1/r⁷. The van der Waals potential, however, varies with 1/r⁶. Recall that force (F) and potential (U) are related by the equation:

(i.e. force is the derivative of potential)

renge ishyo · « **Reply #4 on:** January 05, 2010, 03:34:10 PM »

Yggs is right, the book that I checked only mentioned the potential and not the force.

Topic: Van der Waals forces between molecules (their dependance on distance) (Read 5830 times)

Marija

Van der Waals forces between molecules (their dependance on distance)

renge ishyo

Re: Van der Waals forces between molecules (their dependance on distance)

Marija

Re: Van der Waals forces between molecules (their dependance on distance)

Yggdrasil

Re: Van der Waals forces between molecules (their dependance on distance)

renge ishyo

Re: Van der Waals forces between molecules (their dependance on distance)

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