Abstract
We prove that for a single-component many-body system at zero temperature the inequality E_ int ≤ PV holds, where E_ int is the interaction energy, P is pressure and V is volume. This inequality is proven under rather general assumptions with the use of Anderson-type bound relating ground state energies of systems with different numbers of particles. We also consider adding impurity particles to the system and derive inequalities on the chemical potential of the impurity and binding energy of the bound state of two impurities.