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Input Capacitance of an op amp

Hi, I have a question regarding to input capacitance of an op amp. The file attached is my simulation on op amp AD8034 using LTSpice. the roll-off frequency will give me the common mode input capacitance value: C=1/(2pi*f*R) which is equals to 1.14pF. That's the value obtained from my simulation. However, the value provided in datasheet is 2.3pF. So, I'm a bit confused, is it there's a mistake with my circuit or I read wrongly on the datasheet? The common mode input impedence value provided is 1000||2.3, unit Gohm||pF, the capacitance stated is actually included both inverting and non-inverting input pin or just non-inverting input pin? Thanks.