Fix(hsolver): add early PW basis-size guard to report npw<nbands clearly

[Cstandardlib]

Linked Issue

Fix #7201

Description

• Add a pre-check in HSolverPW before iterative diagonalization.
• Abort early when current k-point plane-wave dimension is smaller than nbands, and print solver name, k-point index, npw(dim), and nbands with actionable hints.
• Avoid opaque downstream failures such as psi_norm <= 0.0 in under-complete basis cases.
• Keep behavior unchanged for valid basis dimensions

[Copilot]

Pull request overview

Adds an early validation in the PW Hamiltonian solver to fail fast (with a clearer, more actionable error) when the plane-wave basis at a k-point is too small for the requested number of bands, preventing obscure downstream solver failures (Issue #7201).

Changes:

• Add an early guard in HSolverPW::hamiltSolvePsiK for npw(dim) < nbands, emitting additional diagnostic context before aborting.
• Reuse cached dim/nband values when calling the CG diagonalizer.
• Minor whitespace tweak to an atomic-structure notice message.

Reviewed changes

Copilot reviewed 1 out of 2 changed files in this pull request and generated 5 comments.

File	Description
source/source_hsolver/hsolver_pw.cpp	Introduces the early PW basis-size guard and threads dim/nband through the CG diagonalization call.
source/source_cell/check_atomic_stru.cpp	Adjusts formatting of a user-facing “Notice” message (leading space).

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[Copilot]

The guard compares dim = psi.get_current_ngk() (which appears to be the local number of plane waves on the current rank after PW distribution) against nband. In MPI runs it’s common for a rank’s local npw to be < nbands even when the global PW dimension (sum over POOL_WORLD) is sufficient, so this can abort valid parallel calculations. Consider reducing dim over POOL_WORLD (sum) to a global npw_k for the current k-point and compare that against nband (and optionally print both local and global dims).

[Copilot]

ik (1-based) = nk_nums + 1 is misleading: nk_nums is passed as this->wfc_basis->nks (total k-points in the pool) at the call sites, not the current k-point index. Prefer using psi.get_current_k() (after psi.fix_k(ik)) or pass the actual ik into hamiltSolvePsiK, otherwise the reported k-point will be wrong.

[Copilot]

The detailed diagnostics are printed via multiple std::cout lines, but WARNING_QUIT only records a short message in warning.log (rank 0) and will also print its own standardized NOTICE block. To keep the actionable details in logs and avoid duplicated multi-rank stdout spam, consider composing a single descriptive message (e.g., with std::stringstream) and passing it to WARNING_QUIT, and/or gate extra stdout logging to GlobalV::MY_RANK==0.

[Copilot]

This whitespace-only change to the emitted warning text (adding a leading space before "Notice") is unrelated to the PR’s stated purpose (HSolverPW early basis-size guard). If it’s intentional, it should be called out in the PR description; otherwise consider reverting it to keep the change set focused.

[Copilot]

The new under-complete-basis guard introduces an important new failure mode/message, but there doesn’t appear to be a unit test exercising HSolverPW::hamiltSolvePsiK for npw_k < nbands. If feasible, add a small gtest that constructs a Psi with ngk[k]=dim<nbands and asserts the code aborts with the expected message (or throws in UT builds) to prevent regressions.