低温二维电子气体的比热容

运用闭路格林函数方法，得到了二维电子气体热力学势的表达式，同时还得到了新的交换项，这个交换项可以化为已知的由虚时方法得到的表达式，但在低温下它没有奇异性，这表明，虽然闭路格林函数方法和虚时方法在总体上是等价的，但在一些技术细节上前者优于后者，此外，从导出的热力学势出发计算了二维电子气体在低温下的比热容。

The Specific Heat of the Two-Dimensional Electron Gas at Low Temperature

By the closed path Green function appraoch an explicit expression of the thermo dynamic potential with a new form of the exchange term for the two dimensional electron gas was derived. It is shown that this exchange term can be reduced to the conventional one resulted from the imaginary time formalism, but at low temperature it has no singularity. This means that, though the closed path Green function appraoch and the imaginary time one are equivalent as a whole, for some technical details, the former is superior to the latter. Starting from this thermo dynamic potential the specific heat of the electron gas at low temperature was calculated.