Can I Include author login in post class?

Yes, you can do it pretty easily using get_the_author_meta function and post_class filter:

function add_author_nicename_to_post_class( $classes, $class, $post_id ) {
    $classes[] = get_the_author_meta( 'user_nicename' );

    return $classes;
}
add_filter( 'post_class', 'add_author_nicename_to_post_class', 10, 3 );