Train times for early March aren't yet on the Renfe website but looking at the times for next Monday as a guide shows that there are just 4 departures each day, at 0652, 0748, 1231 and 1251.
Departing at 0652 can get you to Barcelona Sants at 1420, with a connection at Sevilla Santa Justa. However you can pay a lower fare if you depart on the same train but change at Madrid Atocha instead, arriving 22 minutes later, at 1442
It's a VERY long journey if you elect to depart at 0748. Although it's a direct train, it's a very slow service and doesn't get you into Barcelona Sants until 2005.
Leaving at 1231 can get you to Barcelona Sants at 1930, changing at Madrid Atocha.
A departure at 1251 will get you to Barcelona Sants at 2022, with a change at Sevilla Santa Justa.
Once it's got a little closer to your departure date, search and book here:
https://www.renfe.com/es/en
(NB: Book in advance. Tickets on, or close to, the date of travel can be far more expensive!)