What is the author's purpose for writing "The Raven"?

This is largely a thematic question. I don't know if Poe had ever stated his reason for writing the Raven but we can look for clues in the themes of the poem. There are many themes you might consider in the Raven. I am partial to "The subconscious self". You can check out this and other themes at the GradeSaver link below.