RESUMEN
Using the B3PW method we simulate the ground state of H center systems for CaF(2) and BaF(2) crystals. The energy difference between H centers with different orientations shows that the H center oriented in the [111] direction in alkaline earth fluorides is the most stable. We present the geometric relaxations of the neighboring atoms surrounding the H center. The combination energy of an H center and the formation energy of the related F-H pair in both alkaline earth fluorides are discussed. We also report the electronic structure of the H center systems. The effective charges and spins of the substitutional and interstitial fluorine atoms show that the hole is located at the interstitial fluorine. The band structures are presented. By studying the DOS sketches the constituents of the defect bands are clarified.