[ase-users] QMMM simulation of metal cation hydration

[nancy]

Hi I am a new person to ASE and I am trying to do QMMM simulation of metal cation hydration. I wonder how to build a system like 58 water molecules and 1 Na(+) molecule?

I tried:


from ase.calculators.tip4p import TIP4P, rOH, angleHOH, epsilon0, sigma0

a1 = Atom(’Na', position=[0,0,0], charge = +1)

x = angleHOH * np.pi / 180 / 2
pos = [[0, 0, 0],
       [0, rOH * np.cos(x), rOH * np.sin(x)],
       [0, rOH * np.cos(x), -rOH * np.sin(x)]]
a2 = Atoms('OH2', positions=pos)
vol = ((18.01528 / 6.022140857e23) / (0.9982 / 1e24))**(1 / 3.)
a2.set_cell((vol, vol, vol))
a2.center()
a2 *= 48
a2.set_cell((0,0,0))

atoms = a1 + a2

But this give me TypeError: unsupported operand type(s) for +: 'Atom' and ‘Atoms’

How could I fix it?
Thank you for your help

Best wishes

Nancy
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