Bus from San Pedro de Atacama to Antofagasta, Chile?

My English is not so good but you can seek for Turbus buses. The bus company covers all Chile ;-)

Bon voyage

The ease of searching and booking bus schedules in Chile online has improved since this question was posted; you can look at recorrido.cl to check schedules and book. Searching that website for an arbitrarily-selected date a few weeks from now shows three services per day offered by Pullman Bus, though of course things may vary. Travelers who do not have a Chilean debit or credit card can pay by PayPal.

Particularly outside of peak season, though, it is probably also completely fine to just stop by the bus station in San Pedro and ask around; the bus station is easy to find and an easy walking distance from the main tourist center of town. As other posters have mentioned, you may have more options for travel time if you are willing to connect in Calama, and it is easy to ask about this if you talk to the bus companies in person.