 
Summary: FOCUS 7
New Avenues for Quantum Monte
Carlo Techniques
D.Alfè*andM.J.Gillan,*DepartmentofEarthSciences, DepartmentofPhysicsand
Astronomy,UniversityCollegeLondon
N.D.Drummond,M.D.TowlerandR.J.Needs,CavendishLaboratory,UniversityofCambridge
The Holy Grail of condensed matter physics is the
ability to solve the 78 year old Schrödinger equation
for "reallife" systems. The great difficulty is that the
motions of the electrons in molecules and crystals are
correlated because of the strong repulsion between
their negative charges. The solution of the many
electron Schrödinger equation (the wavefunction) is
therefore a complicated function of 3N variables,where
N is the number of electrons in the system. A boost to
the field was given by Hohenberg and Kohn (HK) 40
years ago [1],with the introduction of density functional
theory (DFT). They showed that it was possible to
reformulate quantum mechanics in such a way that
the important physical quantity is the electron density,
