mirror of https://gitlab.com/QEF/q-e.git
57 lines
3.0 KiB
Plaintext
57 lines
3.0 KiB
Plaintext
This example shows how to calculate the minimum energy path (MEP)
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by using the nudged elastic band (NEB) method in conjunction with
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the Effective Screening Medium Method (ESM) and two constant bias potential
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methods (FCP & GCSCF)
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Before starting this example, see also examples for the ESM method and
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two constant bias potential methods (FCP & GCSCF) in pw.x
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(PW/examples/ESM_example).
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The example calculations are divided into the following three parts,
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1) NEB example with ESM, constant-N calculation (run_example_ESM)
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2) NEB example with FCP, constant-mu calculation (run_example_FCP)
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3) NEB example with GCSCF, constant-mu calculation (run_example_GCSCF)
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The 'run_example' file executes the above three calculations.
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1) NEB example with ESM, constant-N calculation (run_example_ESM)
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1-1) make an NEB calculation for H atom diffusion on Al(001) surface with
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ESM (bc3). This calculation shows the MEP of H atom (Bridge site ->
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top site -> bridge site).
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(input=Al001+H_bc3.in, output=Al001+H_bc3.out).
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Excess charge & Fermi energy at initial geometry)
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tot_charge = 0.0
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Fermi energy = -4.5 eV
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1-2) repeat #1-1 with tot_charge = 0.0215 (positively charged surface)
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(input=Al001+H_bc3_n215.in, output=Al001+H_bc3_n215.out).
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Excess charge & Fermi energy at initial geometry)
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tot_charge = 0.0215
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Fermi energy = -5.0 eV (i.e. applied potential =-0.5 V vs PZC)
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2) NEB example with FCP, constant-mu calculation (run_example_FCP)
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2-1) repeat #1-2 under a constant bias potential condition using FCP.
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The target Fermi energy is -5.0 eV.
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(input=Al001+H_FCP_vm05.in, output=Al001+H_FCP_vm05.out)
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NB----------------------------------------------------------------
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| i) If first_last_opt = .FLASE. (default) |
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| Need to specify the TOTAL_CHARGE card in the initial and final |
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| geometries to set the Fermi energy of those systems to become |
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| a desired value. For intermediate images, the initial charge |
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| of the system is given by lenear interpolation between |
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| the first and the last configurations. |
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| ii) If first_last_opt = .TRUE. |
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| FCP can converge to the target Fermi energy without specifying |
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| the TOTAL_CHARGE card, but you can get better convergence if |
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| you specify it. |
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------------------------------------------------------------------
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3) NEB example with GCSCF, constant-mu calculation (run_example_GCSCF)
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3-1) repeat #1-2 under a constant bias potential condition using GCSCF.
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The target Fermi energy is -5.0 eV.
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(input=Al001+H_GCSCF_vm05.in, output=Al001+H_GCSCF_vm05.out)
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NB------------------------------------------------------------------
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| No need to specify the TOTAL_CHARGE card. GCSCF is automatically |
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| converged to the target Fermi energy. |
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--------------------------------------------------------------------
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