To coordinate WordPress with your server, You need to do a few things. These configurations help you use WordPress and themes better.
Please read the below links:
https://webnus.ticksy.com/article/4415/
https://codex.wordpress.org/Editing_wp-config.php#Increasing_memory_allocated_to_PHP
500 Internal server error causes from web site's server and it is not related to the theme.
Please read the following article:
http://pcsupport.about.com/od/findbyerrormessage/a/500servererror.htm