创建原子符号
在弯曲的箭头上旋转带有自定义箭头的B样条曲线，以此创建一个原子符号.
Animate[Graphics[{EdgeForm[Gray], Red, Disk[{0, 0}, .05], StandardGray, Arrowheads[Table[{0.02, p + t, Graphics[{EdgeForm[StandardGray], Hue[2 t], Disk[]}]}, {p, {0, 0.5}}]], GeometricTransformation[Arrow[BSplineCurve[{{-1, 0}, {0, -(1 / 4)}, {1, 0}, {0, 1 / 4}}, SplineDegree -> 3, SplineClosed -> True]], Table[RotationMatrix[(θ + 90 t) °], {θ, 0, 135, 45}]]}, PlotRange -> 2 / 3, ImageSize -> Medium], {t, 0, 0.5}]