Add a notice for deepks_v_delta.

Author: ErjieWu

docs/advanced/input_files/input-main.md

@@ -2258,7 +2258,7 @@ Warning: this function is not robust enough for the current version. Please try
 
 - **Type**: int
 - **Availability**: Numerical atomic orbital basis
-- **Description**: Include V_delta/V_delta_R (Hamiltonian in k/real space) label for DeePKS training. When `deepks_out_labels` is true and `deepks_v_delta` > 0 (k space), ABACUS will output `deepks_hbase.npy`, `deepks_vdelta.npy` and `deepks_htot.npy`(htot=hbase+vdelta). When `deepks_out_labels` is true and `deepks_v_delta` < 0 (real space), ABACUS will output `deepks_hrtot.csr`, `deepks_hrdelta.csr`. Some more files output for different settings.
+- **Description**: Include V_delta/V_delta_R (Hamiltonian in k/real space) label for DeePKS training. When `deepks_out_labels` is true and `deepks_v_delta` > 0 (k space), ABACUS will output `deepks_hbase.npy`, `deepks_vdelta.npy` and `deepks_htot.npy`(htot=hbase+vdelta). When `deepks_out_labels` is true and `deepks_v_delta` < 0 (real space), ABACUS will output `deepks_hrtot.csr`, `deepks_hrdelta.csr`. Some more files output for different settings. *NOTICE: To match the unit Normally used in DeePKS, the unit of Hamiltonian in k space is Hartree. However, currently in R space the unit is still Ry.*
   - `deepks_v_delta` = 1: `deepks_vdpre.npy`, which is used to calculate V_delta during DeePKS training.
   - `deepks_v_delta` = 2: `deepks_phialpha.npy` and `deepks_gevdm.npy`, which can be used to calculate `deepks_vdpre.npy`. A recommanded method for memory saving.
   - `deepks_v_delta` = -1: `deepks_vdrpre.npy`, which is used to calculate V_delta_R during DeePKS training.