Non-simple behavior of simple metals at high pressure

Experimental and theoretical high-pressure research on simple metals is reviewed. It is shown that simple metals undergo transition sequences from close-packed highly-symmetric to less-symmetric and often less closely packed structures as pressure is varied over a wide range. A number of theoretical perspectives concerning the nature of this behavior are reviewed with a focus on the electrophysical properties of lithium and calcium at high pressure. Static and shock-wave compression data on Li and Ca are presented.