After the battle of Borodino Franz Roubaud worked on a great panorama painting of 115 meters long.
looking at the big panorama painting by Franz Roubaud I noticed that some of the Russian imperial army soldiers were wearing what almost seemed like Santa hats.(Mitre caps as explained in answer)
If I am not mistaken this is frame two of the panorama painting.
What are these hats and the function of those wearing them?
My first guess would be they are officers or special units/soldiers, but a search on the internet did not help.