Parameter: ntime

Definition

Number of imaginary time slices sampling by continuous time or Hirsch-Fye quantum Monte Carlo quantum impurity solver.

In the iQIST software package, the imaginary time mesh is calculated as follows:

$$\tau_i = \frac{\beta (i-1)}{n-1}$$

where $i \in [1,n]$ and $\tau_i \in [0,\beta]$. So, the value of $n$ is just ntime.

Type

Integer

Default value

1024 (for CT-HYB impurity solvers) or 64 (for HF-QMC impurity solvers)

Component

ALL

Behavior

Determine the size of involved arrays, such as the imaginary-time Green's function $G(\tau)$, the hybridization function $\Delta(\tau)$, the auxiliary correlation function $F(\tau)$, the spin-spin correlation function $\langle S_z(0) S_z(\tau) \rangle$, etc.

Comment

The ntime = 1024 is an optimal value for most cases. But if the system temperature is too low, it is useful to increase ntime to obtain higher accurate. For example, if $\beta = 100$, it is better to let ntime = 2048 or 4096.

See mfreq and nfreq parameters for more details.