Bose-Einstein condensates of microwave-shielded polar molecules

We investigate the ground-state properties of the ultracold gases of bosonic microwave-shielded polar molecules. To account for the large shielding core of the inter-molecular potential, we adopt a variational ansatz incorporating the Jastrow correlation factor. We show that the system is always stable and supports a self-bound gas phase and an expanding gas phase. We also calculate the condensate fraction which is significantly reduced when the size of the shielding core of the two-body potential becomes comparable to the inter-molecular distance. Our studies distinguish the molecular condensates from the atomic ones and invalidate the application of the Gross-Pitaevskii equation to the microwave-shielded molecular gases. Our work paves the way for studying the Bose-Einstein condensations of ultracold gases of microwave-shielded polar molecules.