Stochastic equations for fluctuating potentials in the donor–acceptor systems with low compensation

To solve the stochastic equations for fluctuating potentials in donor?acceptor systems with low compensations $K$, an asymptotic perturbation theory is elaborated and a correction to the Fermi level of impurity electrons is calculated: $\delta\mu(K)=c_1K+c_2K^{3/2}+c_3K^2\log(1/K)+c_4K^2$. The constants $c_i$ are an asymptotic series in the powers of $\alpha=0.23$ with coefficients depending on $\Lambda$, where $1/\Lambda$ is the mean size of the local two-acceptor complex. The constant $c_1$ is proportional to $\Lambda$. Thus, despite the low compensation of two-acceptor local complexes, their structure determines the leading term of the asymptotic behavior of $\delta\mu(K)$.