A phase diagram in a jar

One of the things I love about colloids is just how visual they are. Be it watching them jiggling around under a confocal microscope, or the beautiful TEM images of crystal structures, I always find them quite inspirational, or at least instructional, for better understanding statistical mechanics. Sedimentation Just to prove I’m on the cutting edge of science, I recently discovered another neat example from 1993. At the liquid matter conference in Vienna Roberto Piazza gave a talk titled “The unbearable heaviness of colloids”....

November 7, 2011 · 3 min · Douglas Ashton

Back from the dead

Can’t remember the number of times I’ve said I’ve been away because I’ve been busy, but this time it’ll be different. Well it probably won’t be different, it looks like I’m destined to be an inconsistent blogger! It’s now been three months since I arrived in the Netherlands for my new job and I’m enjoying it a lot here. The pace is much faster in the group than I’m used to but I’m enjoying the buzz of lots of interesting things getting done....

November 4, 2011 · 3 min · Doug

Universality at the critical point

Time for more critical phenomena. Another critical intro I’ve talked about this a lot before so I will only very quickly go back over it. The phase transitions you’re probably used to are water boiling to steam or freezing to ice. Now water is, symmetrically, very different from ice. So to go from one to the other you need to start building an interface and then slowly grow your new phase (crystal growth)....

July 9, 2011 · 3 min · Douglas Ashton

An early look at simulation

While I was putting together the post on 2D disks I came across a lovely paper from 1962 on 2D melting by Alder and Wainwright. From there I found this paper from 1959: Studies in Molecular Dynamics. I. General Method by the same authors. They describe the “event driven” molecular dynamics (MD) algorithm. Normally, with MD you calculate forces, and thus accelerations, and update this way. Hard disks or spheres behave more like snooker balls, the forces are more or less instantaneous impulses that conserve momentum so it’s better to deal with collision events and leave out the acceleration part....

April 27, 2011 · 5 min · Douglas Ashton

Lipid membranes on the arXiv

A while ago I discussed lipid membranes and how they could exhibit critical behaviour. There were some lovely pictures on criticality on giant unilamellar vesicles (GUVs) which are sort of model cell walls. That work was done by Sarah Keller and friends in Seattle. This morning on the arXiv I saw this new paper, also by Sarah: Dynamic critical exponent in a 2D lipid membrane with conserved order parameter They look at the critical dynamics of the GUV’s surface....

April 15, 2011 · 1 min · Douglas Ashton