Well now I have learnt something! On reflection however it could be obvious. "Deaths at Sea" were recorded in the Ship's Log which the Captain would deliver on arrival - and as Smith didn't arrive no one handed in the Log. This would mean that all the details of what happened were taken from the survivors and no "official" record of the voyage exists. This would however seem to answer your original question as to death certificates - no there were none. However there must have been certificates for the comparatively few who were identified and buried in Newfoundland(?) - I do not think you can bury anyone anywhere in a "civilised" country without a death certificate? As so many of the victims were the 3rd class passengers I would think it possible that no one had any reason for certificates, they would just have accepted it. However, if you are looking for someone who had property or family I suppose they would have had to be "declared" dead for inheritance purposes, so perhaps you should try either of those routes? I hasten to add I know nothing about how one goes about "declaring dead" or exactly how it is done and recorded. I believe one has to wait seven years if a person has just "disappeared". In the case of the Titanic it should be pretty obvious they had died - but there could have been a couple who were rescued but did not want to be found so cleared off under another name? Best of luck anyway.