Published online by Cambridge University Press: 19 January 2010
Let us consider an open region, i.e., one in which particles can come and go freely, drawn in a system of infinite extent. What will now be shown is that the fluctuation in the number of particles in this region is given by the volume integral of g(r) – 1, which is specifically the isothermal compressibility of the liquid. Another interesting example of such a relation between fluctuations and thermodynamic quantities yields the specific heat cv; this is discussed in Appendix A5.4.
One reason for the interest in the above relation between the volume integral of the radial distribution function—or, equivalently, from (2.4), the long wavelength limit of the structure factor S(k)—and the compressibility (first derived by Ornstein and Zernike) is because of the difficulty of extending diffraction experiments to very small scattering angles.
Let us consider a member of the grand canonical ensemble in which the open region, of volume V, contains exactly N particles.
To save this book to your Kindle, first ensure [email protected] is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Find out more about the Kindle Personal Document Service.
To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Dropbox.
To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.