\ = 1; (*gyromagnetic ratio*)
m0 = {1, 0, 0}; (*initial magnetization*)
b = {0, 0, 1}; (*external magnetic field*)
T1 = 1; T2 = 1; (*relaxation times*)
meq = {0, 0, 0.1}; (*equilibrium magnetization*)
matrix := {{-1/T2, \ B3, -\Gamma B2}, {-\Gamma B3, -1/T2, \Gamma B1}, {\Gamma B2, -\Gamma B1, -1/T1}}; (*evolution matrix*)
dt = 0.05; (*time step*)
m = m0;
evo = ReapDo
     m = m/Normm; (*make sure the vector is normalized*)
     m = m + dt*(matrixb . m + meq/T1);
     Sowm
     , 10002, 1;
frames = Table
   Graphics3D{
     Black, Sphere{0, 0, 0}, 0.05, Sphereevoj, 0.02, Thick, Line{{0, 0, 0}, evoj},
     Orange, Lineevo1 ;; j ,
     Black, Arrow{{-1, -1, 0}, {-1, -1, 0.8}},
     TextStyle"\!\(\*SubscriptBoxOverscriptBox\(B\), \(\Rule\), \\(ext\)\)", Black, Bold, {-1, -1, 1},
     Thin, Gray, 
     Line{{-1, -1, 0}, {-1, 1, 0}, {1, 1, 0}, {1, -1, 0}, {-1, -1, 0}},
     Black, Thick,
     Arrow{{-1, 1, 0}, {-1, 1, 0.5}}, 
     Arrow{{-1, 1, 0}, {-0.5, 1, 0}}, 
     Arrow{{-1, 1, 0}, {-1, 0.5, 0}},
     TextStyle"y", Black, Bold, {-0.4, 1, 0},
     TextStyle"x", Black, Bold, {-1, 0.4, 0},
     TextStyle"z", Black, Bold, {-1, 1, 0.6}
     }, PlotRange -> {{-1.2, 1.2}, {-1.2, 1.2}, {0, 1.2}}, 
    Boxed -> False, ImageSize -> 400
   , {j, 2, 1000, 5};
ListAnimateframes