isotope definition + excited states

General discussion of the Cambridge quantum Monte Carlo code CASINO; how to install and setup; how to use it; what it does; applications.

isotope definition + excited states

Postby s.nasiri » Wed Sep 25, 2013 12:07 pm

Dear all

first:
How I can define isotop for an atom in CASINO? (vi input file or gwfn.data)
second:
wave function file's name for excited state is (for example) gwfn.data or sth else?
and If I perpare wave function from gaussian how can I prepare gwfn.data file? is the process is different?

Your Sincerely
S. nasiri
s.nasiri
 
Posts: 16
Joined: Sun Jun 02, 2013 11:41 am

Re: isotop definition

Postby Mike Towler » Wed Sep 25, 2013 1:24 pm

How I can define isotop for an atom in CASINO? (vi input file or gwfn.data)


As CASINO doesn't do proper dynamics, the nuclear mass is only important in CASINO for calculating the mass polarization term when doing perturbative relativistic corrections to energies - which I guess you're probably not doing. But for what it's worth, CASINO by default uses a nuclear mass which is averaged over isotopes in the proper proportion. If you want to use a different value (such as the mass of a given single isotope) you can use the input keyword isotope_mass.

Code: Select all
1x64:pc53% casinohelp isotope_mass
 CASINO HELP SYSTEM
 ==================

 Keyword : isotope_mass
 Title   : Nuclear mass override
 Type    : Double Precision
 Level   : Expert

 DESCRIPTION
 -----------
 This keyword can be used to define the nuclear mass (in amu) if one wishes
 to override the default value (which is averaged over isotopes according to
 their abundances).  The default is used if ISOTOPE_MASS is set to zero. The
 atomic mass unit (amu) in this sense means 'the ratio of the average mass per
 atom of the element to 1/12 of the mass of 12C.


wave function file's name for excited state is (for example) gwfn.data or sth else?


gwfn.data.

and If I perpare wave function from gaussian how can I prepare gwfn.data file? is the process is different?


First of all, there is a fairly comprehensive discussion of that in the 'How to use GAUSSIAN to prepare trial wave functions' part of the manual (linked top left). Read that first.

All trial wave function states for real systems with atoms, ground and excited, are just one or more determinants containing orbitals which can be specified in the gwfn.data format. These can be generated directly in GAUSSIAN or whatever (in which case you need to read the GAUSSIAN manual for whatever technique you choose to do that), or you can take whatever is in the gwfn.data file, e.g. the Hartree-Fock ground state determinant, and use it as a reference configuration. The 'MDET' block in the correlation.data file allows one either to use the reference configuration or to specify excitations, additions or subtractions from the reference configuration. Furthermore, it enables the user to construct an expansion in several determinants with optimizable expansion coefficients. See the discussion of the correlation.data file in the manual.

Mike
Mike Towler
 
Posts: 234
Joined: Thu May 30, 2013 11:03 pm
Location: Florence

Re: isotop definition

Postby s.nasiri » Sat Oct 12, 2013 6:40 pm

Dear Dr. Towler

I tested the excited options for the CASINO example (He) in correlation.data file recently, but there is no difference in energy(both vmc and vmc_dmc).
In addition I cant understand the band expression in the CASINO manual (page 63).
Also I want to convert TDHF to qmc, but the excited states couldn't be read by gaussiantoqmc. I would be appreciated If you help me.

Your Sincerely
S. Nasiri
======================================================
correlation.data


Code: Select all
START JASTROW
 Title
 Helium atom
 Truncation order C
   3
 START U TERM
 Number of sets
   1
 START SET 1
 Spherical harmonic l,m
   0 0
 Expansion order N_u
   6
 Spin dep (0->uu=dd=ud; 1->uu=dd/=ud; 2->uu/=dd/=ud)
   0
 Cutoff (a.u.)     ;  Optimizable (0=NO; 1=YES)
   3.03628341264640                1
 Parameter values  ;  Optimizable (0=NO; 1=YES)
   1.50854092172728D-002           1           ! alpha_0,1
   3.74543964432219D-003           1           ! alpha_2,1
  -4.37507961332673D-003           1           ! alpha_3,1
   3.46828619163808D-003           1           ! alpha_4,1
  -1.43187283101090D-003           1           ! alpha_5,1
   2.35867141651134D-004           1           ! alpha_6,1
 END SET 1
 END U TERM
 START CHI TERM
 Number of sets
   1
 START SET 1
 Spherical harmonic l,m
   0 0
 Number of atoms in set
   1
 Labels of the atoms in this set
    1
 Impose electron-nucleus cusp (0=NO; 1=YES)
   0
 Expansion order N_chi
   6
 Spin dep (0->u=d; 1->u/=d)
   0
 Cutoff (a.u.)     ;  Optimizable (0=NO; 1=YES)
   4.52474807651525                1
 Parameter values  ;  Optimizable (0=NO; 1=YES)
  -1.56464406832965D-002           1
  -1.97925337767574D-003           1
   9.38296433176895D-004           1
  -1.15945983513531D-003           1
   3.47964127487651D-004           1
  -4.13740807702531D-005           1
 END SET 1
 END CHI TERM
 START F TERM
 Number of sets
   1
 START SET 1
 Number of atoms in set
   1
 Labels of the atoms in this set
    1
 Prevent duplication of u term (0=NO; 1=YES)
   0
 Prevent duplication of chi term (0=NO; 1=YES)
   0
 Electron-nucleus expansion order N_f_eN
   3
 Electron-electron expansion order N_f_ee
   3
 Spin dep (0->uu=dd=ud; 1->uu=dd/=ud; 2->uu/=dd/=ud)
   0
 Cutoff (a.u.)     ;  Optimizable (0=NO; 1=YES)
   4.93715229458050                1
 Parameter values  ;  Optimizable (0=NO; 1=YES)
  -3.89448785479647D-005           1
  -5.59412445469341D-005           1
   2.09099988523118D-005           1
   3.43710687217248D-005           1
  -2.16909362651536D-005           1
   4.65968939890769D-006           1
   4.88040770166266D-005           1
   1.12994795693989D-005           1
  -1.04593194539963D-005           1
   5.58294492382233D-006           1
   2.16160349570317D-005           1
  -1.40959372243613D-005           1
  -1.87618616049162D-005           1
   3.93895641010750D-006           1
   9.97996950307559D-006           1
   7.25991266293985D-007           1
  -9.70371031087955D-007           1
   1.26332945099827D-005           1
  -1.56884862602524D-005           1
   1.32429264810658D-006           1
   2.43922348328098D-005           1
  -3.69004324128847D-006           1
  -2.14664207938044D-008           1
  -1.77962267378144D-006           1
   1.87605978869879D-007           1
   1.14185858809273D-007           1
 END SET 1
 END F TERM
 END JASTROW
START MDET
 Title
 MDET example: use a single-determinant excited state.
 Multideterminant/excitation specification (see manual)
 SD
   DET 1 2 PR 2 1 5 1
 END MDET
s.nasiri
 
Posts: 16
Joined: Sun Jun 02, 2013 11:41 am

Re: isotop definition

Postby Mike Towler » Mon Oct 14, 2013 11:18 am

I tested the excited options for the CASINO example (He) in correlation.data file recently, but there is no difference in energy(both vmc and vmc_dmc).

That's because:

(1) the He atom has two electrons, one in an up-spin spin orbital, the other in a down-spin spin orbital. Both orbitals are the ground state spin-orbitals (i.e. they have orbital sequence number '1'). Yet you are telling CASINO to promote an electron from the second down-spin orbital to the fifth. Neither of these are occupied in the ground-state, so clearly this promotion will have no effect.

(2) Ordinarily CASINO would whine about your above error; I imagine the reason it isn't is that you're using numerical atomic orbitals (i.e. an awfn.data trial wave function file) in which case you then need to specify the excitation in the awfn.data file. While this is actually stated in the manual, I appreciate it could be a little more prominent - I will try to make it so.

In addition I cant understand the band expression in the CASINO manual (page 63).

I don't know what you're referring to. There's nothing I would understand as a 'band expression' on p. 63 of the current manual.
.
Also I want to convert TDHF to qmc, but the excited states couldn't be read by gaussiantoqmc. I would be appreciated If you help me.

I don't have a license to run Gaussian, I'm afraid - and so I've never used the Gaussian to CASINO converter. The CASINO manual states that the converter supports TDHF. If it doesn't then you need to file a proper bug report. Obviously I can't sensibly comment based on the information you've provided.

Mike
Mike Towler
 
Posts: 234
Joined: Thu May 30, 2013 11:03 pm
Location: Florence

Re: isotope definition

Postby s.nasiri » Sun Dec 24, 2017 7:06 am

Dear Dr. Mike Towler

I have a question about considering mass polarization in relativistic correction.
1) Is it possible to define a special isotope for more than one element?
for example H and Li in LiH molecule?
2) Casino manual page 173-174:
"If there is just one nucleus present then all finite-mass effects are accounted
for to O(M−1); otherwise some finite-mass effects are neglected. "
Could you explain what kind of terms are neglected? or give me some references ?

thanks
Saeed Nasiri
s.nasiri
 
Posts: 16
Joined: Sun Jun 02, 2013 11:41 am


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