I'd say there isn't really. A penalty is given because it is literally giving the attacking side the easiest possible means of scoring a goal. Given which, for a highly-paid professional whose main purpose is scoring goals to miss such an opportunity is very much professional negligence.
It most definitely is not. It may be a grave error, but professional negligence it most certainly isn't.
For a footballer to be guilty of professional negligence, he would need to fail to turn up on time for kick off. Once he is on the pitch he is performing tasks which, by their very nature, are prone to failure. If they were not, every game would finish 0-0.