We present an analytical expression for the local-field factor G(q) of the homogeneous electron gas which reproduces recently published quantum Monte Carlo data by Moroni, Ceperley, and Senatore ͓Phys. Rev. Lett. 75, 689 ͑1995͔͒, reflects the theoretically known asymptotic behaviors for both small-and large-q limits, and allows us to express the exchange-correlation kernel K xc analytically in both the direct and reciprocal space. The last property is particularly useful in numerical applications to real solids. ͓S0163-1829͑98͒04823-1͔

An exchange-correlation energy functional beyond the local density approximation, based on the exchange-correlation kernel of the homogeneous electron gas and originally introduced by Kohn and Sham, is considered for electronic structure calculations of semiconductors and atoms. Calculations are carried out for diamond, silicon, silicon carbide and gallium arsenide. The lattice constants and gaps show a small improvement with respect to the LDA results. However, the corresponding corrections to the total energy of the isolated atoms are not large enough to yield a substantial improvement for the cohesive energy of solids, which remains hence overestimated as in the LDA.

The European Union low-carbon strategy includes a range of complementary policies. Potential interactions between instruments and different timing of their implementation can influence the cost and likelihood of achieving the targets. We test the interactions between the three main pillars of the European Union strategy through a dynamic Computable General Equilibrium model (GDynEP) with a time horizon of 2050. Main results are: i) going for the unilateral European Union carbon mitigation target without any complementary technological policy will produce large economic losses; ii) by investing in clean energy technologies (energy efficiency and renewable energy) with a carbon tax revenue recycling mechanism, these losses will decrease substantially; iii) when complementary clean energy technology policies are implemented, the optimal timing of binding targets changes; iv) the higher the public support to clean energy technologies, the larger the economic gains in early adoption of challenging abatement targets.

No abstract

No abstract