[QE-users] scf of orthorhombic structure

[Pooja Vyas]

And the reference with which I'm comparing the lattice parameters, has
define structure with Pnam space group. Then wouldn't it also have volume
according to V=abc?

On Tue, 26 Oct 2021, 3:49 pm Pooja Vyas, <poojavyas595 at gmail.com> wrote:

> Then according to it, shouldn't I be using the formula V=abc?
>
> On Tue, Oct 26, 2021 at 3:47 PM Pooja Vyas <poojavyas595 at gmail.com> wrote:
>
>> Dear user,
>> my lattice parameters are in agreement with
>> https://materialsproject.org/materials/mp-560885/. For which I've used
>> ibrav=8 which is for primitive.
>>
>> On Tue, Oct 26, 2021 at 3:35 PM Kazume NISHIDATE <nisidate at iwate-u.ac.jp>
>> wrote:
>>
>>>
>>> I don't know what type of primitive vectors you are choosing, but the
>>> difference of the volumes may originate from the difference of their
>>> definitions.
>>>
>>> The simple orthorhombic Bravais lattice is identical to the
>>> conventional cell with the volume of V=abc. While the volume of the
>>> primitive face-centered orthorhombic unit cell is V=abc/4.
>>> In your system, 45x4 => 180 is close to your value of 176.
>>>
>>> see eg.
>>> http://aflowlib.org/prototype-encyclopedia/orthorhombic_lattice.html
>>>
>>> best regards
>>> kazume NISHIDATE
>>> 敬具 西館数芽
>>>
>>> nisidate at iwate-u.ac.jp
>>> kazume.nishidate at gmail.com
>>>
>>>
>>> 2021年10月26日(火) 17:52 Pooja Vyas <poojavyas595 at gmail.com>:
>>>
>>>> Dear users,
>>>>
>>>> I required optimized lattice parameters of orthorhombic CaSiO3 for
>>>> which I executed variable cell relaxation. The equilibrium volume obtained
>>>> was 176 ang^3 while the reported ones are around 45 ang^3. The optimized
>>>> lattice constant agrees well with reported data. Can I know how to convert
>>>> lattice parameters a, b, c of orthorhombic CaSiO3 into volume?
>>>>
>>>> Also If I require a lattice constant-energy curve, should I change all
>>>> lattice constants a, b, and c with equal step size and run an scf at all
>>>> points?
>>>>
>>>> Regards.
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>>
>>
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