### How to obtain the transient reflectivity/absorption using Yambo

Posted:

**Thu Jan 23, 2020 2:20 pm**Dear Developers,

I am keen to learn the the calculation of transient reflectivity or absorption using YAMBO code. To learn that I am following a paper (https://journals.aps.org/prb/abstract/1 ... .93.195205) on bulk silicon where the transient reflectivity is calculated using Bethe Salpeter level as implemented in Yambo. I could obtain the following

i) I could reproduce the G0W0+BSE spectrum first

ii) Then I did a real time approach to obtain the optical spectrum which looks like as obtained from BSE. Following input is used for real time simulation

Yambo_rt -q p gives

negf # [R] Real-Time dynamics

HXC_Potential= "HARTREE+SEX" # [SC] SC HXC Potential

GfnQPdb= "E < SAVE/ndb.QP" # [EXTQP G] Database

GfnQP_N= 1 # [EXTQP G] Interpolation neighbours

% GfnQP_E

0.000000 | 1.000000 | 1.000000 | # [EXTQP G] E parameters (c/v) eV|adim|adim

%

GfnQP_Z= ( 1.000000 , 0.000000 ) # [EXTQP G] Z factor (c/v)

GfnQP_Wv_E= 0.000000 eV # [EXTQP G] W Energy reference (valence)

% GfnQP_Wv

0.00 | 0.00 | 0.00 | # [EXTQP G] W parameters (valence) eV| 1|eV^-1

%

GfnQP_Wv_dos= 0.000000 eV # [EXTQP G] W dos pre-factor (valence)

GfnQP_Wc_E= 0.000000 eV # [EXTQP G] W Energy reference (conduction)

% GfnQP_Wc

0.00 | 0.00 | 0.00 | # [EXTQP G] W parameters (conduction) eV| 1 |eV^-1

%

GfnQP_Wc_dos= 0.000000 eV # [EXTQP G] W dos pre-factor (conduction)

% RTBands

4 | 5 | # [RT] Bands

%

Integrator= "RK2" # [RT] Integrator. Use keywords space separated ( "EULER/EXPn/INV" "SIMPLE/RK2/RK4/HEUN" "RWA")

PhLifeTime= 0.000000 fs # [RT] Dephasing Time

RTstep=10.000000 as # [RT] Real Time step length

NETime=55.000000 fs # [RT] Simulation Time

% IOtime

0.05 | 0.10 | 0.10 | fs # [RT] Time between to consecutive I/O (OBSERVABLEs,CARRIERs - GF - OUTPUT)

%

% Field1_Freq

0.00 | 0.00 | eV # [RT Field1] Frequency

%

Field1_Int=1000.000000 kWLm2 # [RT Field1] Intensity

Field1_Width= 0.000000 fs # [RT Field1] Width

Field1_kind= "DELTA" # [RT Field1] Kind(SIN|RES|ANTIRES|GAUSS|DELTA|QSSIN)

Field1_pol= "linear" # [RT Field1] Pol(linear|circular)

% Field1_Dir

0.000000 | 1.000000 | 0.000000 | # [RT Field1] Versor

%

% Field1_Dir_circ

0.000000 | 0.000000 | 0.000000 | # [RT Field1] Versor_circ

%

Field1_Tstart= 0.010000fs # [RT Field1] Initial Time

However, I don not know how to set the parameter for pumb probe set up with a time delay using yambo to obtain the transient spectrum. I did not find any tutorials which talks about this. Can anybody help me in this regard.

Regards,

Bramhachari Khamari

I am keen to learn the the calculation of transient reflectivity or absorption using YAMBO code. To learn that I am following a paper (https://journals.aps.org/prb/abstract/1 ... .93.195205) on bulk silicon where the transient reflectivity is calculated using Bethe Salpeter level as implemented in Yambo. I could obtain the following

i) I could reproduce the G0W0+BSE spectrum first

ii) Then I did a real time approach to obtain the optical spectrum which looks like as obtained from BSE. Following input is used for real time simulation

Yambo_rt -q p gives

negf # [R] Real-Time dynamics

HXC_Potential= "HARTREE+SEX" # [SC] SC HXC Potential

GfnQPdb= "E < SAVE/ndb.QP" # [EXTQP G] Database

GfnQP_N= 1 # [EXTQP G] Interpolation neighbours

% GfnQP_E

0.000000 | 1.000000 | 1.000000 | # [EXTQP G] E parameters (c/v) eV|adim|adim

%

GfnQP_Z= ( 1.000000 , 0.000000 ) # [EXTQP G] Z factor (c/v)

GfnQP_Wv_E= 0.000000 eV # [EXTQP G] W Energy reference (valence)

% GfnQP_Wv

0.00 | 0.00 | 0.00 | # [EXTQP G] W parameters (valence) eV| 1|eV^-1

%

GfnQP_Wv_dos= 0.000000 eV # [EXTQP G] W dos pre-factor (valence)

GfnQP_Wc_E= 0.000000 eV # [EXTQP G] W Energy reference (conduction)

% GfnQP_Wc

0.00 | 0.00 | 0.00 | # [EXTQP G] W parameters (conduction) eV| 1 |eV^-1

%

GfnQP_Wc_dos= 0.000000 eV # [EXTQP G] W dos pre-factor (conduction)

% RTBands

4 | 5 | # [RT] Bands

%

Integrator= "RK2" # [RT] Integrator. Use keywords space separated ( "EULER/EXPn/INV" "SIMPLE/RK2/RK4/HEUN" "RWA")

PhLifeTime= 0.000000 fs # [RT] Dephasing Time

RTstep=10.000000 as # [RT] Real Time step length

NETime=55.000000 fs # [RT] Simulation Time

% IOtime

0.05 | 0.10 | 0.10 | fs # [RT] Time between to consecutive I/O (OBSERVABLEs,CARRIERs - GF - OUTPUT)

%

% Field1_Freq

0.00 | 0.00 | eV # [RT Field1] Frequency

%

Field1_Int=1000.000000 kWLm2 # [RT Field1] Intensity

Field1_Width= 0.000000 fs # [RT Field1] Width

Field1_kind= "DELTA" # [RT Field1] Kind(SIN|RES|ANTIRES|GAUSS|DELTA|QSSIN)

Field1_pol= "linear" # [RT Field1] Pol(linear|circular)

% Field1_Dir

0.000000 | 1.000000 | 0.000000 | # [RT Field1] Versor

%

% Field1_Dir_circ

0.000000 | 0.000000 | 0.000000 | # [RT Field1] Versor_circ

%

Field1_Tstart= 0.010000fs # [RT Field1] Initial Time

However, I don not know how to set the parameter for pumb probe set up with a time delay using yambo to obtain the transient spectrum. I did not find any tutorials which talks about this. Can anybody help me in this regard.

Regards,

Bramhachari Khamari