rt-TDDFT with NVE ensemble: total energy drifts upward and diverges for 2D material

[lwei755]

Describe the bug

When running real-time TDDFT (rt-TDDFT) for 2D hexagonal boron nitride (h-BN) with NVE ensemble, the total energy keeps increasing and eventually diverges. Since NVE ensemble should strictly conserve total energy, this indicates a potential numerical instability or parameter issue.
Important note: The simulation was performed after a complete structural relaxation (geometry optimization) of the 2D h-BN system. The relaxed structure was used as the starting point for rt-TDDFT/NVE simulation.
Control test – H2 molecule (from official example)

As a benchmark, I tested the official H2 molecule example provided by ABACUS under the same NVE + rt-TDDFT settings. The results show good total energy conservation with no divergence.

INPUT_PARAMETERS
#Parameters (1.General)
suffix hBN
calculation md
esolver_type tddft
nbands 432
nspin 1
pseudo_dir .
orbital_dir .
#Parameters (2.Iteration)
ecutwfc 60
scf_thr 1e-7
scf_nmax 100
#Parameters (3.Basis)
basis_type lcao
gamma_only 0
#Parameters (4.Smearing)
smearing_method gauss
smearing_sigma 0.0001
vdw_method d3_bj
dft_functional pbe
#Parameters (5.MD Parameters)
td_propagator 0
md_type nve
md_nstep 10000
md_dt 0.001
md_tfirst 0

#KPT file
K_POINTS
0
Gamma
4 4 1 0 0 0

#STRU file:
ATOMIC_SPECIES
B 10.81 B_ONCV_PBE-1.0.upf
N 14.007 N_ONCV_PBE-1.0.upf

NUMERICAL_ORBITAL
B_gga_7au_100Ry_2s2p1d.orb
N_gga_7au_100Ry_2s2p1d.orb

LATTICE_CONSTANT
1.8897261258369282

LATTICE_VECTORS
7.53728468436000 0.00000000000000 0.00000000000000
-3.7686423421800 6.52748001221100 0.00000000000000
0.00000000000000 0.00000000000000 27.7072650000000

ATOMIC_POSITIONS
Direct

B
0.00000000000000
18
0.11111111111100 0.22222222222200 0.43045808563200 1 1 1 mag 0.0
0.11111111111100 0.55555555555600 0.43045808563200 1 1 1 mag 0.0
0.11111111111100 0.88888888888900 0.43045808563200 1 1 1 mag 0.0
0.44444444444400 0.22222222222200 0.43045808563200 1 1 1 mag 0.0
0.44444444444400 0.55555555555600 0.43045808563200 1 1 1 mag 0.0
0.44444444444400 0.88888888888900 0.43045808563200 1 1 1 mag 0.0
0.77777777777800 0.22222222222200 0.43045808563200 1 1 1 mag 0.0
0.77777777777800 0.55555555555600 0.43045808563200 1 1 1 mag 0.0
0.77777777777800 0.88888888888900 0.43045808563200 1 1 1 mag 0.0
0.00000000000000 0.00000000000000 0.56954191436800 1 1 1 mag 0.0
0.00000000000000 0.33333333333300 0.56954191436800 1 1 1 mag 0.0
0.00000000000000 0.66666666666700 0.56954191436800 1 1 1 mag 0.0
0.33333333333300 0.00000000000000 0.56954191436800 1 1 1 mag 0.0
0.33333333333300 0.33333333333300 0.56954191436800 1 1 1 mag 0.0
0.33333333333300 0.66666666666700 0.56954191436800 1 1 1 mag 0.0
0.66666666666700 0.00000000000000 0.56954191436800 1 1 1 mag 0.0
0.66666666666700 0.33333333333300 0.56954191436800 1 1 1 mag 0.0
0.66666666666700 0.66666666666700 0.56954191436800 1 1 1 mag 0.0

N
0.00000000000000
18
0.11111111111100 0.22222222222200 0.56954191436800 1 1 1 mag 0.0
0.11111111111100 0.55555555555600 0.56954191436800 1 1 1 mag 0.0
0.11111111111100 0.88888888888900 0.56954191436800 1 1 1 mag 0.0
0.44444444444400 0.22222222222200 0.56954191436800 1 1 1 mag 0.0
0.44444444444400 0.55555555555600 0.56954191436800 1 1 1 mag 0.0
0.44444444444400 0.88888888888900 0.56954191436800 1 1 1 mag 0.0
0.77777777777800 0.22222222222200 0.56954191436800 1 1 1 mag 0.0
0.77777777777800 0.55555555555600 0.56954191436800 1 1 1 mag 0.0
0.77777777777800 0.88888888888900 0.56954191436800 1 1 1 mag 0.0
0.22222222222200 0.11111111111100 0.43045808563200 1 1 1 mag 0.0
0.22222222222200 0.44444444444400 0.43045808563200 1 1 1 mag 0.0
0.22222222222200 0.77777777777800 0.43045808563200 1 1 1 mag 0.0
0.55555555555600 0.11111111111100 0.43045808563200 1 1 1 mag 0.0
0.55555555555600 0.44444444444400 0.43045808563200 1 1 1 mag 0.0
0.55555555555600 0.77777777777800 0.43045808563200 1 1 1 mag 0.0
0.88888888888900 0.11111111111100 0.43045808563200 1 1 1 mag 0.0
0.88888888888900 0.44444444444400 0.43045808563200 1 1 1 mag 0.0
0.88888888888900 0.77777777777800 0.43045808563200 1 1 1 mag 0.0

Expected behavior

No response

To Reproduce

No response

Environment

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Additional Context

No response

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