9 research outputs found
X-ray diffraction data as a source of the vibrational free-energy contribution in polymorphic systems
Electron-density studies on hydrogen bonding in chromone derivatives. Part II: comparative study
The modern molecular clock
The discovery of the molecular clock - a relatively constant rate of molecular evolution-provided an insight into the mechanisms of molecular evolution, and created one of the most useful new tools in biology. The unexpected constancy of rate was explained by assuming that most changes to genes are effectively neutral. Theory predicts several sources of variation in the rate of molecular evolution, However, even an approximate clock allows time estimates of events in evolutionary history, which provides a method for testing a wide range of biological hypotheses ranging from the origins of the animal kingdom to the emergence of new viral epidemics
Electron densities and related properties from the ab-initio simulation of crystalline solids
Cryo-Crystallography: Diffraction at Low Temperature and More
This chapter comments on the motivations and the methods of crystallographic studies at low temperature. Cry-crystallography is a brunch of Crystallography, a science that is too often confused with a technique. On the other hand, the scientific background to study crystal phases at low temperature is here provided, together with a survey of many possible techniques that provide complementary or supplementary information. Several applications are discussed, in particular in relation with highly accurate studies like electron density determination or phase transition mechanisms. © 2011 Springer-Verlag Berlin-Heidelberg