72 lines
1.9 KiB
Markdown
72 lines
1.9 KiB
Markdown
```python
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import matplotlib.pyplot as plt
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import numpy as np
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from pint import UnitRegistry
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# Set up unit system
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unit = UnitRegistry()
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unit.formatter.default_format = "~"
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unit.setup_matplotlib()
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# Physical constants
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e=-1.602176634e-19 * unit.C # electron charge
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m=9.109e-31 * unit.kg # electron mass
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hbar=6.62607015e-34/2/np.pi * unit.joule * unit.second # Planck constant
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phi=4 * unit.eV # Work function (see table)
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phi_joule=phi.to("joule")
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U=5 *unit.V
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# Table working functions different metals
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# Metal F(eV)
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# (Work Function)
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# Ag (silver) 4.26
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# Al (aluminum) 4.28
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# Au (gold) 5.1
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# Cs (cesium) 2.14
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# Cu (copper) 4.65
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# Li (lithium) 2.9
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# Pb (lead) 4.25
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# Sn (tin) 4.42
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# Chromium 4.6
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# Molybdenum 4.37
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# Stainless Steel 4.4
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# Gold 4.8
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# Tungsten 4.5
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# Copper 4.5
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# Nickel 4.6
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# Distance range
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Distance_tip_sample=np.linspace(10e-13,2e-10,100)* unit.m
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Tunneling_current=U*np.exp(-2*np.sqrt(2*m*phi_joule)/hbar*Distance_tip_sample) /unit.V #please note: This is not the tunneling current as this formular gives just the proportionality. Calculating the current constant is difficult as there are for us unknown parameters
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Distance_tip_sample_nm=Distance_tip_sample.to("nm")
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plt.plot(Distance_tip_sample_nm, Tunneling_current)
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plt.xlabel(f"Distance tip sample [{Distance_tip_sample_nm.units:~P}]")
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plt.ylabel(f"Tunneling-Proportionality [arb. Unit]")
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plt.xticks(ticks=np.linspace(0, 0.2, 5), labels=[f"{x:.2f}" for x in np.linspace(0, 0.2, 5)])
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#plt.yscale("log")
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```
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([<matplotlib.axis.XTick at 0x7e10b04929b0>,
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<matplotlib.axis.XTick at 0x7e10b04b0310>,
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<matplotlib.axis.XTick at 0x7e10b034ba60>,
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<matplotlib.axis.XTick at 0x7e10b0328670>,
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<matplotlib.axis.XTick at 0x7e10b0329360>],
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[Text(0.0, 0, '0.00'),
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Text(0.05, 0, '0.05'),
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Text(0.1, 0, '0.10'),
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Text(0.15000000000000002, 0, '0.15'),
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Text(0.2, 0, '0.20')])
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