update the doc

Author: kirk0830

docs/advanced/input_files/input-main.md

@@ -154,6 +154,7 @@
     - [out\_mat\_dh](#out_mat_dh)
     - [out\_mat\_xc](#out_mat_xc)
     - [out\_mat\_xc2](#out_mat_xc2)
+    - [out\_mat\_l](#out_mat_l)
     - [out\_eband\_terms](#out_eband_terms)
     - [out\_hr\_npz/out\_dm\_npz](#out_hr_npzout_dm_npz)
     - [dm\_to\_rho](#dm_to_rho)
@@ -1807,6 +1808,13 @@ The band (KS orbital) energy for each (k-point, spin, band) will be printed in t
 - **Description**: Whether to print the exchange-correlation matrices in **numerical orbital representation** (unit: Ry): $\braket{\phi_i|V_\text{xc}^\text{(semi-)local}+V_\text{exx}+V_\text{DFTU}|\phi_j}(\mathbf{R})$ in CSR format (the same format as [out_mat_hs2](../elec_properties/hs_matrix.md#out_mat_hs2)) in the directory `OUT.${suffix}`. (Note that currently DeePKS term is not included. ) The files are named `Vxc_R_spin$s`.
 - **Default**: False
 
+### out_mat_l
+
+- **Type**: Boolean [Integer\](optional)
+- **Availability**: Numerical atomic orbital (NAO) basis
+- **Description**: Whether to print the expectation value of the angular momentum operator $\hat{L}_x$, $\hat{L}_y$, and $\hat{L}_z$ in the basis of the localized atomic orbitals. The files are named `OUT.${suffix}/${suffix}_Lx.dat`, `OUT.${suffix}/${suffix}_Ly.dat`, and `OUT.${suffix}/${suffix}_Lz.dat`. The second integer controls the precision of the output.
+- **Default**: False 8
+
 ### out_eband_terms
 
 - **Type**: Boolean