Making a 1-way spin wave packet

[dovod91]

Dear Team,

Thank you again for the software and your support.

I am struggling to code a 1-way spin wave packet for my simulations.
The pulse should be in the form:

sin(w t - k x) = sin(k x) sin(w t) + cos(k x) cos(w t) [1]

Therefore, it is my understanding that I should end up adding an energy term in the system in the form of:

system.energy += mm.Zeeman(H=H, func=func, dt=dt_)

where H is my 'spatial' field profile, and 'func' can be my time-dependent field, together making the final expression for the field.
So far, and by checking with the API, my current code looks like this:

# Field in space:
def field_1_sin_spat(point):
    x, y, z = point

    k_0 = 0.175*2*3.14*1e6 # 0.175 rad/um
    sr2_x = 5*10e-9
    
    c_k = 0.1*k_0
    a_1 = 1/(2*(c_k)**2)
    t_0 = 1e-10

    Amp = 80e0
    gauss_x = np.exp( -((x+sr2_x)**2) / (4*a_1) )

    field_1 = (Amp*np.sin(k_0 * x)*gauss_x, 0, 0)

    return (Amp*np.sin(k_0 * x)*gauss_x, 0, 0)

# Field in space:
def field_2_cos_spat(point):
    x, y, z = point

    k_0 = 0.175*2*3.14*1e6 # 0.175 rad/um
    sr2_x = 5*10e-9
    
    c_k = 0.1*k_0
    a_1 = 1/(2*(c_k)**2)
    t_0 = 1e-10

    Amp = 80e0
    gauss_x = np.exp( -((x+sr2_x)**2) / (4*a_1) )

    field_2 = (Amp*np.cos(k_0 * x)*gauss_x, 0, 0)

    return (Amp*np.cos(k_0 * x)*gauss_x, 0, 0)

H_1_sin = df.Field(mesh, nvdim=3, value=field_1_sin_spat)
H_2_cos = df.Field(mesh, nvdim=3, value=field_2_cos_spat)

The time-dependent fields:

def field_1_sin_time(t):
    
    omega = 2*3.14*1e9 # 1 GHz
    
    c_w = 0.4*omega
    b_1 = 1/(2*(c_w)**2)
    t_0 = 2e-9

    return np.sin(omega*t)*np.exp(-((t-t_0)**2) / (4*b_1))


def field_2_cos_time(t):
   
    omega = 2*3.14*1e9 # 1 GHz
    
    c_w = 0.4*omega
    b_1 = 1/(2*(c_w)**2)
    t_0 = 2e-9

    return np.cos(omega*t)*np.exp(-((t-t_0)**2) / (4*b_1))

So the system should be:

system.energy += mm.Zeeman(H=H, func=field_1_sin_time, name='field1', dt=dt_)    # first term of [1]
system.energy += mm.Zeeman(H=H, func=field_2_cos_time, name='field2', dt=dt_)    # second term of [1]

I am not obtaining what expected: While for a certain point, the coded wave packet shows only two maxima, in the simulation there are more travelling maxima through that point:

Maybe there is an easier way to code this 1-way pulse in ubermag? Thank you so much for your suggestions.

Best regards,