publications - Is it OK to write first initial of some authors on a paper and full first name of others?

Suppose there are two authors Albert Einstein and Isaac Newton on a research paper. Is it OK to write them as A. Einstein and Isaac Newton or vice versa? Similarly, if there are more authors, is it OK to write initials of some of them and not all? If it is not OK, is it wrong and unacceptable, or bad?

My question is about writing the authors' names on the top, with the title of the paper.