I'm sorry, but Robert Frost did not create a poem called "A Holocaust Called Hiroshima." In fact, I am not aware of any poem by Robert Frost with that title or on that subject. Robert Frost is a renowned American poet known for his works such as "The Road Not Taken," "Stopping by Woods on a Snowy Evening," and "Mending Wall," among others.
It's possible that there is a poem with that title by another author, but I am not aware of it. The bombing of Hiroshima, which took place in 1945 during World War II, has been the subject of many literary works, including poems, novels, and essays. Some poets who have written about this event include Allen Ginsberg, Robert Lowell, and Richard Wilbur, among others.