Variational Monte-Carlo investigation of gossamer-superconductivity

Motivated by the interesting superconducting properties in layered organic materials, and the proposed gossamer superconductivity in this context, we performed variational Monte-Carlo simulations. We investigate a previously proposed model-Hamiltonian of a Hubbard-model with additional anti-ferromagnetic coupling term. We work on a square lattice with additional diagonal bonds and with a wave-function with partly projected double-occupied states. Further factors for anti-ferromagnetic states are introduced in our wave-function.