Fix Compute_Ratio_Global call sites for log-scale signature change

[Copilot]

Compute_Ratio_Global signature changed to accept log_T0_proposal_ratio but two call sites (Langevin HMC and parallel tempering) were not updated.

Changes

Prog/Langevin_HMC_mod.F90

• Variable: T0_Proposal_ratio → log_T0_Proposal_ratio
• Value: 1.0 → 0.0d0
• Function call updated to pass log value

Prog/Global_mod.F90 (Exchange_Step)

• Variable: T0_Proposal_ratio → log_T0_Proposal_ratio
• Value: 1.d0 → 0.d0
• Function call updated to pass log value

! Before (causes type mismatch)
T0_Proposal_ratio = 1.0
Ratiotot = Compute_Ratio_Global(..., T0_Proposal_ratio, ...)

! After (log scale)
log_T0_Proposal_ratio = 0.0d0  ! log(1.0) = 0
Ratiotot = Compute_Ratio_Global(..., log_T0_Proposal_ratio, ...)

All three call sites in the codebase now use the log-scale interface consistently.

Original prompt

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This section details on the original issue you should resolve

<issue_title>Global moves with proposal probability on log scale</issue_title>
<issue_description>

In some cases, the proposal probability can be extreamly small or large, reaching the range of double precision. This will cause numerical issues. Hence, the goal is to provide a new subroutine where the T0_proposal_ratio will be on a logarithmic scale. The base implementation can be a wrapper of the current Global_move function to maintain backwards compatibility.</issue_description>

<agent_instructions>There is already an initial implementation of the issue, which introduced the function Global_move_log_T0. In some cases, the proposal probability can be balanced by the Delta_S0_global, so I modified the if condition on low probability in the last commit.
Please check for correctness and possible further improvements.</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes Global moves with proposal probability on log scale #601

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