Quantum molecular dynamics simulations for the nonmetal-to-metal transition in fluid helium

We have performed quantum molecular dynamics simulations for dense helium to study the nonmetal-to-metal transition at high pressures. We present new results for the equation of state and the Hugoniot curve in the warm dense matter region. The optical conductivity is calculated via the Kubo-Greenwood formula from which the dc conductivity is derived. The nonmetal-to-metal transition is identified at about 1 g/ccm. We compare with experimental results as well as with other theoretical approaches, especially with predictions of chemical models.Comment: 4 pages, 5 figure

On "the complete basis set limit" and plane-wave methods in first-principles simulations of water

Water structure, measured by the height of the first peak in oxygen-oxygen radial distributions, is converged with respect to plane-wave basis energy cutoffs for ab initio molecular dynamics simulations, confirming the reliability of plane-wave methods.Comment: 9 pages, 3 figure

Reactor sterile neutrinos, dark energy and the age of the universe

There are indications that the neutrino oscillation data from reactor experiments and the LSND and MiniBooNE experiments show a preference for two sterile neutrino species, both with masses in the eV region. We show that this result has a significant impact on some important cosmological parameters. Specifically, we use a combination of CMB, LSS and SN1A data and show that the existence of two light, sterile neutrinos would rule out the cosmological constant as dark energy at 95% confidence level, and lower the expansion age of the universe to 12.58 \pm 0.26 Gyr.Comment: Accepted for publication in Astronomy & Astrophysics. References added and typos corrected. Added numerical values for w ranges and Delta chi^2. Minor extension of discussio