WordPress limit posts per page

I have the following problem:

I have limited my “posts per page” on all category archive pages in the functions.php like this:

add_filter('pre_get_posts', 'limit_category_posts');
function limit_category_posts($query){
    if ($query->is_category) {
        $query->set('posts_per_page', 5);
    }
    if ($query->is_single()) {
        $query->set('posts_per_page', 50);
    }
    return $query;
}

add_filter('pre_get_posts', 'per_category_basis');
function per_category_basis($query){
    if ($query->is_category) {
        if (is_category('26')){
            $query->set('posts_per_page', 2000);
        }
        if (is_category('27')){
            $query->set('posts_per_page', 2000);
        }
    }
    return $query;
}

This works fine so far. But now I have a single.php – file that reads posts from one category and displays these in a list, like this:

<?php
  query_posts(array(
      'category_name' => $autorsuche,
   ));

   if ( have_posts() ) :
      echo '<br /><h3>Publikationen:</h3><br /><ul class="publications">';
   endif;

   while ( have_posts() ) : the_post();
?>

<li><a href="<?php the_permalink(); ?>" rel="bookmark"><?php the_title(); ?></a>
<?php the_date( 'd.m.Y', '(', ')' ); ?></li> 

<?php
   endwhile;
    echo '</ul>';
    wp_reset_query();
?>

But this list is limited to 5 posts as well since the above filter applies as well. I need this to have a much larger or better no limit at all.

I tried a lot to alter the filter in the functions.php but didn’t find a solution yet.

Any help would be much appreciated!

Thank you!