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CbPotential.cpp
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Created
Tue, Sep 17, 17:26
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text/x-c
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Thu, Sep 19, 17:26 (1 d, 22 h)
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blob
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20793557
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rLAMMPS lammps
CbPotential.cpp
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#include "CbPotential.h"
#include <cmath>
namespace
ATC
{
static
const
double
EPS
=
1.0e-8
;
// Approximates the derivative of phi
double
CbPotential
::
phi_r
(
const
double
&
r
)
const
{
const
double
dr
=
r
*
EPS
;
return
(
phi
(
r
+
dr
)
-
phi
(
r
))
/
dr
;
}
// Approximates the second derivative of phi
double
CbPotential
::
phi_rr
(
const
double
&
r
)
const
{
const
double
dr
=
r
*
EPS
;
return
(
phi_r
(
r
+
dr
)
-
phi_r
(
r
))
/
dr
;
}
// Approximates the third derivative of phi
double
CbPotential
::
phi_rrr
(
const
double
&
r
)
const
{
const
double
dr
=
r
*
EPS
;
return
(
phi_rr
(
r
+
dr
)
-
phi_rr
(
r
))
/
dr
;
}
// Approximates the derivative of rho
double
CbPotential
::
rho_r
(
const
double
&
r
)
const
{
const
double
dr
=
r
*
EPS
;
return
(
rho
(
r
+
dr
)
-
rho
(
r
))
/
dr
;
}
// Approximates the second derivative of rho
double
CbPotential
::
rho_rr
(
const
double
&
r
)
const
{
const
double
dr
=
r
*
EPS
;
return
(
rho_r
(
r
+
dr
)
-
rho_r
(
r
))
/
dr
;
}
// Approximates the third derivative of rho
double
CbPotential
::
rho_rrr
(
const
double
&
r
)
const
{
const
double
dr
=
r
*
EPS
;
return
(
rho_rr
(
r
+
dr
)
-
rho_rr
(
r
))
/
dr
;
}
// Approximates the derivative of the embedding function
double
CbPotential
::
F_p
(
const
double
&
p
)
const
{
const
double
dp
=
p
*
EPS
;
return
(
F
(
p
+
dp
)
-
F
(
p
))
/
dp
;
}
// Approximates the second derivative of the embedding function
double
CbPotential
::
F_pp
(
const
double
&
p
)
const
{
const
double
dp
=
p
*
EPS
;
return
(
F_p
(
p
+
dp
)
-
F_p
(
p
))
/
dp
;
}
// Approximates the third derivative of the embedding function
double
CbPotential
::
F_ppp
(
const
double
&
p
)
const
{
const
double
dp
=
p
*
EPS
;
return
(
F_pp
(
p
+
dp
)
-
F_pp
(
p
))
/
dp
;
}
// Approximates the derivative of phi3.
double
CbPotential
::
phi3_q
(
const
double
&
q
)
const
{
const
double
dq
=
q
*
EPS
;
return
(
phi3
(
q
+
dq
)
-
phi3
(
q
))
/
dq
;
}
// Approximates the second derivative of phi3.
double
CbPotential
::
phi3_qq
(
const
double
&
q
)
const
{
const
double
dq
=
q
*
EPS
;
return
(
phi3_q
(
q
+
dq
)
-
phi3_q
(
q
))
/
dq
;
}
// Compute bond angle jik from the squared length of vectors ij,ik,kj.
double
calculate_theta
(
double
ij2
,
double
ik2
,
double
jk2
)
{
return
acos
(
0.5
*
(
ik2
+
ij2
-
jk2
)
/
sqrt
(
ij2
*
ik2
)
);
}
// Initializes atomic interactions for up to three different terms.
Interactions
::
Interactions
(
int
a
,
int
b
,
int
c
)
{
// bitwise OR combines the terms that are listed
const
int
abc
=
a
|
b
|
c
;
pairwise
=
(
abc
&
PAIRWISE
)
>
0
;
embedding
=
(
abc
&
EAM
)
>
0
;
three_body
=
(
abc
&
THREE_BDY
)
>
0
;
angle_bending
=
(
abc
&
ANGLE_BND
)
>
0
;
}
}
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