Forgive my naivety but it seems to me all the attempts to create useful fusion concentrate on high temps or high pressures or both and samples of fusible material consisting of multiple nuclei.

Is there any research going on in producing fusion on a single pair of nuclei, sequentially?

The LHC accelerates protons nearly to the speed of light and can direct them to hit each other. Deuterons are electrically charged so can be similarly accelerated. LIGO has been built to such exacting standards it can detect movement of thousanths of a protons diameter. Is it therefore not possible to build an apparatus to accelerate deuterons to a precise velocity and in a precise direction so as to precisely hit another deuteron coming in the opposite direction? A sequential stream of deuterons need not fuse 100% of the time as long as enough do to be energy positive.

What am I missing here?