We present a Monte Carlo method for computing the renormalized coupling constants and the critical exponents within renormalization theory. The scheme, which derives from a variational principle, overcomes critical slowing down, by means of a bias potential that renders the coarse grained variables uncorrelated. The two-dimensional Ising model is used to illustrate the method.

Car studied physics and attained a doctorate in 1971 at the Politecnico di Milano. He was an assistant professor at the École Polytechnique Fédérale de Lausanne (EPFL) from 1977 to 1981, employed at the Thomas J. Watson Research Center of IBM from 1981 to 1983, associate professor for physics at SISSA in Trieste (in 1990/91 as full professor) from 1984 to 1990, and professor for physics at the University of Geneva (and director of the IRRMA of EPFL) from 1991 to 1999.  In 1999 he went to Princeton University where he became the Ralph W. Dornte Professor in Chemistry with a simultaneous appointment with the Princeton Institute for the Science and Technology of Materials. He is also a professor in the Theory Department, of the Fritz Haber Institute of the Max Planck Society. He is a member of the Italian Scientists and Scholars in North America Foundation. In 2009 he shared the Dirac Medal with Michele Parrinello for their development of the ab initio molecular dynamics simulation method. The method combines the quantum mechanical density functional theory for calculation of electronic structure with methods of molecular dynamics for the simulation of classical ("Newtonian") atomic movements. They call their procedure ab initio molecular dynamics ; it is also well known as the Car-Parrinello method. Their procedure has found various applications in solid-state physics, biochemistry, chemical physics, and materials science. In 1990 he received the Hewlett-Packard prize of the European Physical Society, in 1995 the Rahman Prize of the American Physical Society, where he is a Fellow, and in 2009 with Parinello the Sidney Fernbach Award of the IEEE. In 2008, he received the Humboldt Foundation Research Award for senior US scientists. He also received the Aneesur Rahman prize in computational physics. In 2016 he was elected to the National Academy of Sciences. In 2016, he was awarded the American Chemical Society's Award in Theoretical Chemistry.