code modification "order by title"

Please i need help i have a page portfolio with this code

if($post->post_parent) {
$children = wp_list_pages(‘sort_column=menu_order&title_li=&child_of=’ . $post->post_parent . ‘&depth=1&echo=0’);
}
else {
$children = wp_list_pages(‘sort_column=menu_order&title_li=&child_of=’ . $post->ID . ‘&depth=1&echo=0’);
}

This code show me the portfolio post in the page in the order of post date.. how i can get it by order of post title?? Please help