nvidia profiling for md (#411)

* nvidia profiling for md

* 1 model

tools/md-benchmark-nsys-profile.py

+import ase
+import ase.io
+import ase.md
+import argparse
+import torchani
+import autonvtx
+import torch
+
+parser = argparse.ArgumentParser()
+parser.add_argument('filename', help="file for the molecule")
+args = parser.parse_args()
+
+molecule = ase.io.read(args.filename)
+model = torchani.models.ANI1x()[0].cuda()
+calculator = model.ase()
+molecule.set_calculator(calculator)
+dyn = ase.md.verlet.VelocityVerlet(molecule, timestep=1 * ase.units.fs)
+
+dyn.run(1000)  # warm up
+
+torch.cuda.cudart().cudaProfilerStart()
+autonvtx(model)
+with torch.autograd.profiler.emit_nvtx(record_shapes=True):
+    dyn.run(10)